VoIP Questions and Answers: 1 :: What kind of equipment do I need? A broadband Internet connection. You can use a regular phone, as long as you connect it to an adapter. However, companies such as Cisco Systems Inc. now make VoIP phones that don't require adapters. The adapter or new VoIP phone connects to a broadband modem. Some VoIP providers can link to an entire home's wiring so adapters aren't required at each extension. 2 :: Is the system as reliable as the old-fashioned network? Early VoIP services often sounded tinny, delayed or digitized. In recent years, the technology has gotten much better, and Guzman & Co. analyst Pat Comack said it won't be long before it achieves the tech industry's vaunted "five 9s" level -- 99.999 percent reliability. For now, VoIP may not be perfect, but cell phones have made people more accepting of less-than-ideal sonic conditions. 3 :: How does VoIP (voice over Internet protocol) work? What makes it different from traditional phone service? Traditionally, a phone conversation is converted into electronic signals that traverse an elaborate network of switches, in a dedicated circuit that lasts the duration of a call. In Voice over Internet Protocol, a conversation is converted to packets of data that flit all over the Internet or private networks, just like e-mails or Web pages, though voice packets get priority status. The packets get reassembled and converted to sound on the other end of the call. 4 :: What Are Some disadvantages of VoIP? If you're considering replacing your traditional telephone service with VoIP, there are some possible differences:

► Some VoIP services don't work during power outages and the service provider may not offer backup power.► Not all VoIP services connect directly to emergency services through 9-1-1.► VoIP providers may or may not offer directory assistance/white page listings. 5 :: What do internet telephony,packet telephony, IP telephony and converged network means? The first thing all mean the same thing. Which is using IP (Internet protocol) for voice services. Some voice networks are only packet-switched and have no access outside of their own VoIP network. Most VoIP networks have a Gateway that connects to a circuit-switched external network which gives them acces to external calling. One of the gateways responsibilites is to convert G.711 Circuit-switched media (typically a T1 provided by a telco company) to the 7.723 Packet-switched media that will traverse the companies VoIP network. A device called a gatekeeper will then convert the IP address (used by H.323 protocol) to a standard telephone number (E.164 address) that can be used for external calling.

A converged network is a network that passes both Voice and Data over the same set of devices. Converged networks generally implement QoS (Quality of service) on all actived network devices to ensure the VoIP has priority over standard data because of it's more rigid demands.  6 :: What are the advantages to VoIP?The big advantage is VoIP may save you money depending on how much you are currently spending for local and long-distance calls. What you will need to do is get the total cost the phone company is charging and compare it against a VoIP plan that interests you. With most plans, you get free calls within the U.S. and Canada for a low flat rate. International calls usually have very low rates with no connection fees. For both residential customers and businesses that make a lot of long distance and international calls, the savings can be several hundred dollars a year.

Another advantage is with the features available with VoIP. Features such as caller ID, call waiting, call forwarding, 3 way conferencing and voice mail are usually included at no extra cost. With the phone company, these services are usually extra.

In addition, you can make free phone calls anywhere there is a high speed Internet connection available. That means you can be in another state or even in another country and make calls as if you were back at your home or business. You will just need to bring your phone adapter along with you and possibly a phone in case one is not available.7 :: What equipments are needed for VoIP?Generally following things are required for voip

1. Broadband connection2. voip phone3. nexton softswitches4. router5. audiocodec6. astric server8 :: What is the biggest disadvantage to going VoIP with my home phone right now?The biggest disadvantage is that currently all VoIP providers to not offer emergency 911 service in all areas. The FCC has recently ruled though that this is a mandatory requirement that must be completed by September 2005.9 :: When can I replace my cell phone with a VoIP phone?Most likely in the next couple of years. Right now cell phone service providers are developing cell phones that can roam for Wifi VoIP or traditional networks in order to give you the greatest savings dependent upon location. Wifi hotspots, however, do not currently cover as much area as cellular does, so it will take providers some time to work this issue out.10 :: I am in business and would like to replace my corporations current PBX system with VoIP. Is this possible?Yes, many companies are doing just this. VoIP is a very cost-effective method for companies who want to upgrade their old PBX systems and VoIP allows for new features that traditional PBX systems simply do not. Also VoIP web conferencing has come of age and also offers cost savings and many new features not available with traditional web conferencing methods. 11 :: How can I use VoIP at home?You can use VoIP at home currently with a free application such as Skype which lets you talk from your PC to another person who also has Skype on their PC for free anywhere in the world. You can also get a VoIP phone with a VoIP service provider or you can use your regular phone with a VoIP telephone adapter plus a service provider.12 :: How does VoIP work?A VoIP gateway converts the analog voice data into digital data packets which are sent over a broadband Internet connection to a VoIP server that forwards the message to the receiving party.13 :: What is Voice Over Internet Protocol (VoIP)?VoIP stands for Voice Over Internet Protocol or Voice Over IP. VoIP is the method by which you can send your voice (analog data) over the Internet (digital data) to an end-user who receives the message.

CCNA Questions and Answers: 1 :: What is the IGP (Interior Gateway Protocol)? Any protocol used by an internetwork to exchange routing data within an autonomous system. E.g. RIP, IGRP and OSPF. 2 :: What is the multicast routing? Sending a message to a group multicast address is called multicasting, and its routing algorithm is called multicast routing. 3 :: What is the Virtual Path? Along any transmission path from a given source to a given destination, a group of virtual circuits can be grouped together into what is called path. 4 :: What is the Virtual Channel? A logical circuit that is created by Virtual channel links. It carries data between two endpoints in a network.The other name for Virtual Channel is Virtual Circuit. 5 :: What is the logical link control? One of two sublayers of the data link layer of OSI reference model, as defined by the IEEE 802 standard. This sublayer is responsible for error detection but not correction, flow control and framing.  6 :: What is the difference between routable and non- routable protocols?Routable protocols can work with a router and can be used to build large networks. Non-Routable protocols are designed to work on small, local networks and cannot be used with a router.7 :: What is the MAU?MAU - Multistation Access Unit8 :: Explain 5-4-3 rule?In a Ethernet network, between any two points on the network, there can be no more than five network segments or four repeaters, and of those five segments only three of segments can be populated.9 :: What is the difference between TFTP and FTP application layer protocols?TFTP - Trivial File Transfer ProtocolA stripped down version of FTP, easy to use and fast. TFTP has no Directory browsing, no Authentication and insecure it can only send and receive files.

FTP - File Transfer ProtocolThe TCP/IP protocol used for transmitting files between network nodes. FTP allows access to both Directories and files, manipulating directories, typing file contents and copying files between hosts.10 :: What is the difference between ARP and RARP?ARP - Address Resolution ProtocolThe protocol that traces IP addresses to MAC addresses.

RARP - Reverse Address Resolution ProtocolThe protocol within the TCP/IP stack that maps MAC addresses to IP addresses. 11 :: What is the ICMP protocol?ICMP - Internet Control Message ProtocolIt is a Network Layer Internet protocol, which can report errors and status information. We can use the ping command to send ICMP echo request messages and record the receipt of ICMP echo reply messages. With these messages, we can detect network or host communication failures and troubleshoot common TCP/IP connectivity problems.

12 :: What is the MAC address?The address for a device as it is identified at the Media Access Control (MAC) layer in the network architecture. MAC address is usually stored in ROM on the network adapter card and is unique.13 :: What is the Attenuation?In communication weakening or loss of signal energy, typically caused by distance.14 :: What is the Cladding?A layer of a glass surrounding the center fiber of glass inside a fiber-optic cable.15 :: What are the NetBIOS and NetBEUI?NetBIOS - Network Basic Input / Output SystemAn application-programming interface (API) that can be used by programs on a local area network (LAN). NetBIOS provides programs with a uniform set of commands for requesting the lower-level services required to manage names, conduct sessions, and send datagrams between nodes on a network.

NetBEUI - NetBIOS Extended User InterfaceAn improved version of the NetBIOS protocol, a network protocol native to Microsoft Networking. It is usually used in small, department-size local area networks (LANs) of 1 to 200 clients. It can use Token Ring source routing as its only method of routing. 16 :: What is the Beaconing?An FDDI frame or Token Ring frame that points to serious problem with the ring, such as a broken cable. The beacon frame carries the address of the station thought to be down.17 :: What is the Terminal Emulation, in which layer it comes?The use of software, installed on PC or LAN server, that allows the PC to function as if it were dumb terminal directly attached to a particular type of mainframe.Telnet is also called as terminal emulation. It belongs to application layer.18 :: What is the Frame relay, in which layer it comes?Frame relay is an industry standard, shared access, switched Data Link Layer encapsulation that services multiple virtual circuits and protocols between connected mechanism.Frame relay is a packet-switched technology.19 :: What is the network Subnet?A subnet is the subdivision of an IP network.20 :: What is the network Brouter?It?s a Hybrid device that combines the features of both bridges and routers. 21 :: How network Gateway is different from Routers?GatewayA device connected to multiple physical TCP/IP networks capable of routing or delivering IP packets between them.

RouterIt?s a layer 3 device that connects 2 different networks and routes packets of data from one network to another. It breaks up Broadcast domain as well as Collision Domain.22 :: What is the Mesh Network?A network in which there are multiple network links between computers to provide multiple paths for data to travel.23 :: What is Passive Topology in ccna?

When the computers on the network simply listen and receive the signal, they are referred to as passive because they don?t amplify the signal in any way.24 :: What are major types of Networks and explain?Peer-to-Peer NetworkComputers can act as both servers sharing resources and as clients using the resources.

Server-based NetworkProvide centralized control of network resources and rely on server computers to provide security and network administration25 :: What is Protocol Data Unit in ccna?The processes at each layer of the OSI model.Layers----------PDUTransport-------SegmentsNetwork---------Packets/DatagramsData Link-------FramesPhysical--------Bits 26 :: What is difference between Baseband and Broadband Transmission in ccna?In a baseband transmission, the entire bandwidth of the cable is consumed by a single signal.In broadband transmission, signals are sent on multiple frequencies, allowing multiple signals to be sent simultaneously.27 :: What are the possible ways of data exchange in ccna?Possible ways of data exchange in ccna are Simplex Half-duplexFull-duplex28 :: What is point-to-point protocol in ccna?An industry standard suite of protocols for the use of point-to-point links to transport multiprotocol datagrams.29 :: What are the two types of Transmission Technology available in ccna?Two types of Transmission Technology available in ccna are Point - to - Point and Broadcast30 :: What are 10Base2, 10Base5 and 10BaseT Ethernet LANs?10Base2 an Ethernet term meaning a maximum transfer rate of 10 Megabits per second that uses baseband signaling, with a contiguous cable segment length of 200 meters (185mts). Known as Thinnet.10Base5 an Ethernet term meaning a maximum transfer rate of 10 Megabits per second that uses baseband signaling, with a contiguous cable segment length of 500 meters. Known as Thicknet.10BaseT an Ethernet term meaning a maximum transfer rate of 10 Megabits per second that uses two pairs of twisted-pair baseband signaling, with a contiguous cable segment length of 100 meters. 31 :: What is RAID in ccna?A method used to standardize and categorize fault-tolerant disk systems. RAID levels provide various mixes of performance, reliability, and cost. Some servers provide three of the RAID levels: Level 0 (striping), Level 1 (mirroring), and Level 5 (striping & parity).32 :: Difference between the Communication and Transmission?Communication is the process of sending and receiving data by means of a data cable that is connected externally.Transmission means the transfer of data from the source to the destination.33 :: What is Subnetting? Why is it used?

Used in IP Networks to break up larger networks into smaller subnetworks. It is used to reduce network traffic, Optimized network performance, and simplify management i.e. to identify and isolate network problems.34 :: What is a VLAN? What does VLAN provide?VLAN - Virtual Local Area NetworkVlan is a logical grouping or segmenting a network connected to administratively defined ports on a switch, they provide Broadcast control, Security and Flexibility.35 :: What is PING utility?PING - Packet Internet GopherA utility that verifies connections to one or more remote hosts. The ping command uses the ICMP echo request and echo reply packets to determine whether a particular IP system on a network is functional. Ping is useful for diagnosing IP network or router failures. 36 :: What is difference between Switch & Hub?Switch:Switches operate at Layer 2 Data Link LayerAddress LearningForward / Filter decision using MAC addressLoop AvoidanceBreakup collision domainsSwitches create separate collision domains but a single broadcast domain

Hub:Hub operates at Layer 1 Physical LayerNo FilteringNo AddressingHub creates single collision domain and single broadcast domainMake forwarding to all the ports when signal is arrived

Basic Networking Questions and Answers: 1 :: How do we convert a numeric IP address like 192.18.97.39 into a hostname like globalguideline.com? Below line will convert a numeric IP address like 192.18.97.39 into a hostname like globalguideline.com

String hostname = InetAddress.getByName("192.18.97.39").getHostName(); 2 :: What are the two types of transmission technology available? Two types of transmission technology available are:(i) Broadcast(ii) point-to-point. 3 :: What are the possible ways of data exchange? (i) Simplex(ii) Half-duplex(iii) Full-duplex. 4 :: What are 10Base2, 10Base5 and 10BaseT Ethernet LANs? 10Base2?An Ethernet term meaning a maximum transfer rate of 10 Megabits per second that uses baseband signaling, with a contiguous cable segment length of 100 meters and a maximum of 2 segments10Base5?An Ethernet term meaning a maximum transfer rate of 10 Megabits per second that

uses baseband signaling, with 5 continuous segments not exceeding 100 meters per segment.10BaseT?An Ethernet term meaning a maximum transfer rate of 10 Megabits per second that uses baseband signaling and twisted pair cabling. 5 :: What is point-to-point protocol? A communications protocol used to connect computers to remote networking services including Internet service providers. 6 :: What is subnet in Networking?A gateway operates at the upper levels of the OSI model and translates information between two completely different network architectures or data formats.7 :: What is subnet? A generic term for section of a large networks usually separated by a bridge or router. 8 :: What is cladding in Networking? A layer of a glass surrounding the center fiber of glass inside a fiber-optic cable. 9 :: What is a Management Information Base (MIB)?A Management Information Base is part of every SNMP-managed device. Each SNMP agent has the MIB database that contains information about the device's status, its performance, connections, and configuration. The MIB is queried by SNMP.10 :: What is RAID? A method for providing fault tolerance by using multiple hard disk drives to get backups of data.  11 :: What is mesh network? A network in which there are multiple network links between computers to provide multiple paths for data to travel. 12 :: What is the Network Time Protocol? A protocol that assures accurate local timekeeping with reference to radio and atomic clocks located on the Internet. This protocol is capable of synchronizing distributed clocks within milliseconds over long time periods. It is defined in STD 12, RFC 1119.13 :: What is a pseudo tty?A pseudo tty or false terminal enables external machines to connect through Telnet or rlogin. Without a pseudo tty, no connection can take place.14 :: What is a DNS resource record? A resource record is an entry in a name server's database. There are several types of resource records used, including name-to-address resolution information. Resource records are maintained as ASCII files. 15 :: Explain the function of Transmission Control Block?A TCB is a complex data structure that contains a considerable amount of information about each connection.  16 :: What is virtual path?Along any transmission path from a given source to a given destination, a group of virtual circuits can be grouped together into what is called path.17 :: What is the difference between an unspecified passive open and a fully specified passive open? An unspecified passive open has the server waiting for a connection request from a client. A fully specified passive open has the server waiting for a connection from a specific client.18 :: What is anonymous FTP and why would you use it?Anonymous FTP enables users to connect to a host without using a valid login and password. Usually, anonymous FTP uses a login called anonymous or guest, with the password usually requesting the user's ID for tracking purposes only. Anonymous FTP is used to enable a large

number of users to access files on the host without having to go to the trouble of setting up logins for them all. Anonymous FTP systems usually have strict controls over the areas an anonymous user can access.19 :: Difference between bit rate and baud rate?Bit rate is the number of bits transmitted during one second whereas baud rate refers to the number of signal units per second that are required to represent those bits.baud rate = bit rate / Nwhere N is no-of-bits represented by each signal shift. 20 :: What are the important topologies for networks? BUS topology:In this each computer is directly connected to primary network cable in a single line.Advantages:Inexpensive, easy to install, simple to understand, easy to extend.STAR topology:In this all computers are connected using a central hub.Advantages:Can be inexpensive, easy to install and reconfigure and easy to trouble shoot physical problems.RING topology:In this all computers are connected in loop.Advantages:All computers have equal access to network media, installation can be simple, and signal does not degrade as much as in other topologies because each computer regenerates it.  21 :: What is the range of IP addresses in the classes of internet addresses? range of IP addresses in the classes of internet addresses are as under...

Class A 0.0.0.0 - 127.255.255.255Class B 128.0.0.0 - 191.255.255.255Class C 192.0.0.0 - 223.255.255.255Class D 224.0.0.0 - 239.255.255.255Class E 240.0.0.0 - 247.255.255.255 22 :: What protocol is used by DNS name servers? DNS uses UDP for communication between servers. It is a better choice than TCP because of the improved speed a connectionless protocol offers. Of course, transmission reliability suffers with UDP.23 :: What is Bandwidth? Every line has an upper limit and a lower limit on the frequency of signals it can carry. This limited range is called the bandwidth.24 :: What is External Data Representation?External Data Representation is a method of encoding data within an RPC message, used to ensure that the data is not system-dependent.25 :: What is frame relay, in which layer it comes? Frame relay is a packet switching technology. It will operate in the data link layer.  26 :: What is Brouter?Hybrid devices that combine the features of both bridges and routers. 27 :: What is ICMP?ICMP is Internet Control Message Protocol, a network layer protocol of the TCP/IP suite used by hosts and gateways to send notification of datagram problems back to the sender. It uses the echo test / reply to test whether a destination is reachable and responding. It also handles both control and error messages.

28 :: What is difference between baseband and broadband transmission? In a baseband transmission, the entire bandwidth of the cable is consumed by a single signal. In broadband transmission, signals are sent on multiple frequencies, allowing multiple signals to be sent simultaneously.29 :: Explain 5-4-3 rule? In a Ethernet network, between any two points on the network, there can be no more than five network segments or four repeaters, and of those five segments only three of segments can be populated.30 :: What is MAU? In token Ring , hub is called Multi station Access Unit(MAU).  31 :: What is the difference between interior and exterior neighbor gateways? Interior gateways connect LANs of one organization, whereas exterior gateways connect the organization to the outside world. 32 :: What is autonomous system?It is a collection of routers under the control of a single administrative authority and that uses a common Interior Gateway Protocol. 33 :: What is a Multi-homed Host?It is a host that has a multiple network interfaces and that requires multiple IP addresses is called as a Multi-homed Host. 34 :: What is silly window syndrome? It is a problem that can ruin TCP performance. This problem occurs when data are passed to the sending TCP entity in large blocks, but an interactive application on the receiving side reads 1 byte at a time.35 :: What is Project 802? It is a project started by IEEE to set standards that enable intercommunication between equipment from a variety of manufacturers. It is a way for specifying functions of the physical layer, the data link layer and to some extent the network layer to allow for inter connectivity of major LAN protocols.It consists of the following:802.1 is an inter networking standard for compatibility of different LANs and MANs across protocols.802.2 Logical link control (LLC) is the upper sublayer of the data link layer which is non-architecture-specific, that is remains the same for all IEEE-defined LANs. Media access control (MAC) is the lower sublayer of the data link layer that contains some distinct modules each carrying proprietary information specific to the LAN product being used. The modules areEthernet LAN (802.3), Token ring LAN (802.4), Token bus LAN (802.5).802.6 is distributed queue dual bus (DQDB) designed to be used in MANs.  36 :: What is Gateway-to-Gateway protocol?It is a protocol formerly used to exchange routing information between Internet core routers. 37 :: What is BGP (Border Gateway Protocol)?It is a protocol used to advertise the set of networks that can be reached with in an autonomous system. BGP enables this information to be shared with the autonomous system. This is newer than EGP (Exterior Gateway Protocol).38 :: What is source route?It is a sequence of IP addresses identifying the route a datagram must follow. A source route may optionally be included in an IP datagram header.39 :: What is NVT (Network Virtual Terminal)?

It is a set of rules defining a very simple virtual terminal interaction. The NVT is used in the start of a Telnet session. 40 :: What is RIP (Routing Information Protocol)? It is a simple protocol used to exchange information between the routers.  41 :: What is Mail Gateway? It is a system that performs a protocol translation between different electronic mail delivery protocols. 42 :: What is SLIP (Serial Line Interface Protocol)?It is a very simple protocol used for transmission of IP datagrams across a serial line. 43 :: What is Kerberos in Networking? It is an authentication service developed at the Massachusetts Institute of Technology. Kerberos uses encryption to prevent intruders from discovering passwords and gaining unauthorized access to files.44 :: What is OSPF? It is an Internet routing protocol that scales well, can route traffic along multiple paths, and uses knowledge of an Internet's topology to make accurate routing decisions.45 :: What is IGP (Interior Gateway Protocol)? It is any routing protocol used within an autonomous system.  46 :: What is EGP (Exterior Gateway Protocol)?It is the protocol the routers in neighboring autonomous systems use to identify the set of networks that can be reached within or via each autonomous system 47 :: What is Proxy ARP? is using a router to answer ARP requests. This will be done when the originating host believes that a destination is local, when in fact is lies beyond router.48 :: Why should you care about the OSI Reference Model?It provides a framework for discussing network operations and design. 49 :: What is NETBIOS and NETBEUI in Networking? NETBIOS is a programming interface that allows I/O requests to be sent to and received from a remote computer and it hides the networking hardware from applications.NETBEUI is NetBIOS extended user interface. A transport protocol designed by Microsoft and IBM for the use on small subnets. 50 :: What is traffic shaping?One of the main causes of congestion is that traffic is often busy. If hosts could be made to transmit at a uniform rate, congestion would be less common. Another open loop method to help manage congestion is forcing the packet to be transmitted at a more predictable rate. This is called traffic shaping. 51 :: What is logical link control? One of two sublayers of the data link layer of OSI reference model, as defined by the IEEE 802 standard. This sublayer is responsible for maintaining the link between computers when they are sending data across the physical network connection.52 :: What is packet filter in Networking?Packet filter is a standard router equipped with some extra functionality. The extra functionality allows every incoming or outgoing packet to be inspected. Packets meeting some criterion are forwarded normally. Those that fail the test are dropped.53 :: What is redirector in Networking?

Redirector is software that intercepts file or prints I/O requests and translates them into network requests. This comes under presentation layer.54 :: What are the different type of networking / internetworking devices?Repeater:Also called a regenerator, it is an electronic device that operates only at physical layer. It receives the signal in the network before it becomes weak, regenerates the original bit pattern and puts the refreshed copy back in to the link.Bridges:These operate both in the physical and data link layers of LANs of same type. They divide a larger network in to smaller segments. They contain logic that allow them to keep the traffic for each segment separate and thus are repeaters that relay a frame only the side of the segment containing the intended recipient and control congestion.Routers:They relay packets among multiple interconnected networks (i.e. LANs of different type). They operate in the physical, data link and network layers. They contain software that enable them to determine which of the several possible paths is the best for a particular transmission. Gateways: They relay packets among networks that have different protocols (e.g. between a LAN and a WAN). They accept a packet formatted for one protocol and convert it to a packet formatted for another protocol before forwarding it. They operate in all seven layers of the OSI model.55 :: What is REX? Request to Exit (REX) - A signal that informs the controller that someone has requested to exit from a secure area.  56 :: What is the difference between routable and non - routable protocols? Routable protocols can work with a router and can be used to build large networks. Non-Routable protocols are designed to work on small, local networks and cannot be used with a router.57 :: What is multicast routing?Sending a message to a group is called multicasting, and its routing algorithm is called multicast routing. 58 :: What is SAP?Series of interface points that allow other computers to communicate with the other layers of network protocol stack is called SAP. 59 :: What are major types of networks and explain?Server-based network.Peer-to-peer network.

Peer-to-peer network, computers can act as both servers sharing resources and as clients using the resources.Server-based networks provide centralized control of network resources and rely on server computers to provide security and network administration.60 :: What are the types of Transmission media? Signals are usually transmitted over some transmission media that are broadly classified in to two categories:-Guided Media:These are those that provide a conduit from one device to another that include twisted-pair, coaxial cable and fiber-optic cable. A signal traveling along any of these media is directed and is contained by the physical limits of the medium. Twisted-pair and coaxial cable use metallic that accept and transport signals in the form of electrical current. Optical fiber is a glass or plastic cable that accepts and transports signals in the form of light.Unguided Media:This is the wireless media that transport electromagnetic waves without using a physical

conductor. Signals are broadcast either through air. This is done through radio communication, satellite communication and cellular telephony.  61 :: What is terminal emulation, in which layer it comes? Telnet is also called as terminal emulation. It belongs to application layer. 62 :: What is MAC address in Networking?The address for a device as it is identified at the Media Access Control (MAC) layer in the network architecture. MAC address is usually stored in ROM on the network adapter card and is unique.63 :: What is difference between ARP and RARP?The address resolution protocol (ARP) is used to associate the 32 bit IP address with the 48 bit physical address, used by a host or a router to find the physical address of another host on its network by sending a ARP query packet that includes the IP address of the receiver.

The reverse address resolution protocol (RARP) allows a host to discover its Internet address when it knows only its physical address.64 :: What are the data units at different layers of the TCP / IP protocol suite?The data unit created at the application layer is called a message, at the transport layer the data unit created is called either a segment or an user datagram, at the network layer the data unit created is called the datagram, at the data link layer the datagram is encapsulated in to a frame and finally transmitted as signals along the transmission media.65 :: What is Protocol Data Unit?The data unit in the LLC level is called the protocol data unit (PDU). The PDU contains of four fields a destination service access point (DSAP), a source service access point (SSAP), a control field and an information field. DSAP, SSAP are addresses used by the LLC to identify the protocol stacks on the receiving and sending machines that are generating and using the data. The control field specifies whether the PDU frame is a information frame (I - frame) or a supervisory frame (S - frame) or a unnumbered frame (U - frame). 66 :: What is attenuation? The degeneration of a signal over distance on a network cable is called attenuation. 67 :: What do you meant by "triple X" in Networks?The function of PAD (Packet Assembler Disassembler) is described in a document known as X.3. The standard protocol has been defined between the terminal and the PAD, called X.28; another standard protocol exists between the PAD and the network, called X.29. Together, these three recommendations are often called "triple X".68 :: What is the minimum and maximum length of the header in the TCP segment and IP datagram? The header should have a minimum length of 20 bytes and can have a maximum length of 60 bytes. 69 :: What is the HELLO protocol used for?The HELLO protocol uses time instead of distance to determine optimal routing. It is an alternative to the Routing Information Protocol.70 :: What are Diagrams and Trigrams?The most common two letter combinations are called as diagrams. e.g. th, in, er, re and an. The most common three letter combinations are called as trigrams. e.g. the, ing, and, and ion. 71 :: What does the Mount protocol do? The Mount protocol returns a file handle and the name of the file system in which a requested file resides. The message is sent to the client from the server after reception of a client's request.

72 :: What is Beaconing?The process that allows a network to self-repair networks problems. The stations on the network notify the other stations on the ring when they are not receiving the transmissions. Beaconing is used in Token ring and FDDI networks. 73 :: What are the advantages and disadvantages of the three types of routing tables?The three types of routing tables are fixed, dynamic, and fixed central. The fixed table must be manually modified every time there is a change. A dynamic table changes its information based on network traffic, reducing the amount of manual maintenance. A fixed central table lets a manager modify only one table, which is then read by other devices. The fixed central table reduces the need to update each machine's table, as with the fixed table. Usually a dynamic table causes the fewest problems for a network administrator, although the table's contents can change without the administrator being aware of the change. 74 :: What is the difference between TFTP and FTP application layer protocols?The Trivial File Transfer Protocol (TFTP) allows a local host to obtain files from a remote host but does not provide reliability or security. It uses the fundamental packet delivery services offered by UDP.The File Transfer Protocol (FTP) is the standard mechanism provided by TCP / IP for copying a file from one host to another. It uses the services offered by TCP and so is reliable and secure. It establishes two connections (virtual circuits) between the hosts, one for data transfer and another for control information.75 :: Difference between the communication and transmission?Transmission is a physical movement of information and concern issues like bit polarity, synchronization, clock etc.Communication means the meaning full exchange of information between two communication media.  76 :: What is virtual channel?Virtual channel is normally a connection from one source to one destination, although multicast connections are also permitted. The other name for virtual channel is virtual circuit.77 :: What is routing region?When hierarchical routing is used, the routers are divided into what we call regions, with each router knowing all the details about how to route packets to destinations within its own region, but knowing nothing about the internal structure of other regions.78 :: What is passive topology?When the computers on the network simply listen and receive the signal, they are referred to as passive because they don?t amplify the signal in any way.Example for passive topology - linear bus79 :: What is wide-mouth frog? Wide-mouth frog is the simplest known key distribution center (KDC) authentication protocol. 80 :: What are Stored procedures?A stored procedure ia s named collection of SQL statements and procedural logic that is compiled, verified and stored in a server database. It is typically treated like any other database object. Stored procedures accept input parameters so that a single procedure can be used over the network by multiple clients using different input data. A single remote message triggers the execution of a collection of stored SQL statements. The results is a reduction of network traffic and better performance. 81 :: What is ACID property?ACID is a term coined by Andrew Router in 1983, which stands for Atomicity, Consistence, Isolation and Durability. 82 :: What are the services provided by the Operating System?

Extended services - These are add-on modular software components that are layered on top of base service. 83 :: List out the benefits obtained by using the Client/Server oriented TP Monitors? Client/Server applications development framework.Firewalls of protection.High availability.Load balancing.MOM integration.Scalability of functions.Reduced system cost. 84 :: What is Client/Server? Clients and Servers are separate logical entities that work together over a network to accomplish a task. Many systems with very different architectures that are connected together are also called Client/Server.85 :: What are the five major technologies that can be used to create Client/Server applications? Database ServersTP MonitorsGroupwareDistributed ObjectsIntranets.  86 :: What is a File server? File servers are useful for sharing files across a network. With a file server, the client passes requests for file records over network to file server.87 :: What are the types of Servers?File serversDatabase servers Transaction servers Groupware servers Object servers Web servers. 88 :: What are the two broad classes of middleware? General middlewareService-specific middleware.89 :: What is Groupware server?Groupware addresses the management of semi-structured information such as text, image, mail, bulletin boards and the flow of work. These Client/Server systems have people in direct contact with other people.90 :: What is meant by Horizontal scaling and Vertical scaling? Horizontal scaling means adding or removing client workstations with only a slight performance impact. Vertical scaling means migrating to a larger and faster server machine or multiservers. 91 :: What are called Fat clients and Fat servers? If the bulk of the application runs on the Client side, then it is Fat clients. It is used for decision support and personal software.If the bulk of the application runs on the Server side, then it is Fat servers. It tries to minimize network interchanges by creating more abstract levels of services.92 :: What is Load balancing? If the number of incoming clients requests exceeds the number of processes in a server class, the TP Monitor may dynamically start new ones and this is called Load balancing.93 :: What is meant by 2-Tier architecture?In 2-tier Client/Server systems, the application logic is either buried inside the user interface on the client or within the database on the server.Example: File servers and Database servers with stored procedures.

94 :: What is meant by 3-Tier architecture?In 3-tier Client/Server systems, the application logic (or process) lives in the middle tier and it is separated from the data and the user interface. In theory, the 3-tier Client/Server systems are more scalable, robust and flexible.Example: TP monitor, Web. 95 :: What is OLTP? In the transaction server, the client component usually includes GUI and the server components usually consists of SQL transactions against a database. These applications are called OLTP (Online Transaction Processing) OLTP Applications typically,Receive a fixed set of inputs from remote clients. Perform multiple pre-compiled SQL comments against a local database. Commit the work and Return a fixed set of results. 96 :: What is meant by Asymmetric Multiprocessing (AMP)?It imposes hierarchy and a division of labor among processors. Only one designated processor, the master, controls (in a tightly coupled arrangement) slave processors dedicated to specific functions.97 :: What are General Middleware? It includes the communication stacks, distributed directories, authentication services, network time, RPC, Queuing services along with the network OS extensions such as the distributed file and print services.98 :: What are Service-specific middleware?It is needed to accomplish a particular Client/Server type of services which includes:-Database specific middlewareOLTP specific middlewareGroupware specific middlewareObject specific middlewareInternet specific middleware andSystem management specific middleware. 99 :: What is meant by Symmentric Multiprocessing (SMP)?It treats all processors as equal. Any processor can do the work of any other processor. Applications are divided into threads that can run concurrently on any available processor. Any processor in the pool can run the OS kernel and execute user-written threads.100 :: What are the functions of the typical server program?It waits for client-initiated requests. Executes many requests at the same time. Takes care of VIP clients first. Initiates and runs background task activity. Keeps running. Grown bigger and faster.  101 :: What is meant by Middleware?Middleware is a distributed software needed to support interaction between clients and servers. In short, it is the software that is in the middle of the Client/Server systems and it acts as a bridge between the clients and servers. It starts with the API set on the client side that is used to invoke a service and it covers the transmission of the request over the network and the resulting response.It neither includes the software that provides the actual service - that is in the servers domain nor the user interface or the application login - that's in clients domain.102 :: What is Message Oriented Middleware (MOM)?MOM allows general purpose messages to be exchanged in a Client/Server system using message queues. Applications communicate over networks by simply putting messages in the queues and getting messages from queues. It typically provides a very simple high level APIs to its services.MOM's messaging and queuing allow clients and servers to communicate across a network

without being linked by a private, dedicated, logical connection. The clients and server can run at different times. It is a post-office like metaphor. 103 :: What are called Non-GUI clients, GUI Clients and OOUI Clients? Non-GUI Client: These are applications, generate server requests with a minimal amount of human interaction.GUI Clients: These are applications, where occasional requests to the server result from a human interacting with a GUI(Example: Windows 3.x, NT 3.5)OOUI clients : These are applications, which are highly-iconic, object-oriented user interface that provides seamless access to information in very visual formats.(Example: MAC OS, Windows 95, NT 4.0) 104 :: What are the Classification of clients?Non-GUI clients - Two types are:-Non-GUI clients that do not need multi-tasking(Example: Automatic Teller Machines (ATM), Cell phone)Non-GUI clients that need multi-tasking(Example: ROBOTs)

GUI clientsOOUI clients 105 :: What are the three types of SQL database server architecture?Process-per-client Architecture. (Example: Oracle 6, Informix )Multithreaded Architecture. (Example: Sybase, SQL server)Hybrid Architecture (Example: Oracle 7)  106 :: What are the main components of Transaction-based Systems? Resource ManagerTransaction Manager andApplication Program.107 :: What is Remote Procedure Call (RPC)?RPC hides the intricacies of the network by using the ordinary procedure call mechanism familiar to every programmer. A client process calls a function on a remote server and suspends itself until it gets back the results. Parameters are passed like in any ordinary procedure. The RPC, like an ordinary procedure, is synchronous. The process that issues the call waits until it gets the results.Under the covers, the RPC run-time software collects values for the parameters, forms a message, and sends it to the remote server. The server receives the request, unpack the parameters, calls the procedures, and sends the reply back to the client. It is a telephone-like metaphor.108 :: What are the characteristics of Client/Server? ServiceShared resourcesAsymmetrical protocolsTransparency of locationMix-and-matchMessage based exchangesEncapsulation of servicesScalabilityIntegrityClient/Server computing is the ultimate "Open platform". It gives the freedom to mix-and-match components of almost any level. Clients and servers are loosely coupled systems that interact through a message-passing mechanism.

109 :: What is Structured Query Langauge (SQL)? SQL is a powerful set-oriented language which was developed by IBM research for the databases that adhere to the relational model. It consists of a short list of powerful, yet highly flexible, commands that can be used to manipulate information collected in tables. Through SQL, we can manipulate and control sets of records at a time.110 :: What are the roles of SQL? SQL is an interactive query language for ad hoc database queries.SQL is a database programming language.SQL is a data definition and data administration language.SQL is the language of networked database serversSQL helps protect the data in a multi-user networked environment.Because of these multifacted roles it plays, physicists might call SQL as "The grand unified theory of database".  111 :: What are all the Base services provided by the OS? Task preemptionTask prioritySemaphoresInterprocess communications (IPC)Local/Remote Interprocess communicationThreadsIntertask protectionMultiuserHigh performance file systemEfficient memory management andDynamically linked Run-time extensions. 112 :: The middleware building block runs on both the client and server sides of an application. It is broken into three categories? Transport stackNetwork OSService-specific middleware.113 :: Explain the building blocks of Client/Server?The client side building block runs the client side of the application.The server side building block runs the server side of the application. 114 :: What are the building blocks of Client/Server?The clientThe server andMiddleware. 115 :: What are called Transactions?The grouped SQL statements are called Transactions (or) A transaction is a collection of actions embused with ACID properties.  116 :: What is the difference between trigger and rule? The triggers are called implicitly by database generated events, while stored procedures are called explicitly by client applications.117 :: What are the types of Transparencies?The types of transparencies the NOS middle ware is expected to provide are:-Location transparencyNamespace transparencyLogon transparencyReplication transparency

Local/Remote access transparencyDistributed time transparencyFailure transparency andAdministration transparency.118 :: What is meant by Asymmetrical protocols?There is a many-to-one relationship between clients and server. Clients always initiate the dialog by requesting a service. Servers are passively awaiting for requests from clients.119 :: TP Monitor does mainly two things extremely well. They are Process management and Transaction management?They were originally introduced to run classes of applications that could service hundreds and sometimes thousands of clients. TP Monitors provide an OS - on top of existing OS - that connects in real time these thousands of humans with a pool of shared server processes.120 :: What is a TP Monitor?There is no commonly accepted definition for a TP monitor. According to Jeri Edwards' a TP Monitor is "an OS for transaction processing". 121 :: What are Super servers? These are fully-loaded machines which includes multiprocessors, high-speed disk arrays for interview I/O and fault tolerant features.122 :: What is a Web server? This new model of Client/Server consists of thin, portable, "universal" clients that talk to super fat servers. In the simplest form, a web server returns documents when clients ask for them by name. The clients and server communicate using an RPC-like protocol called HTTP.123 :: What are the two types of OLTP? TP lite, based on stored procedures. TP heavy, based on the TP monitors. 124 :: What are TP-Lite and TP-Heavy Monitors?TP-Lite is simply the integration of TP Monitor functions in the database engines.TP-Heavy are TP Monitors which supports the Client/Server architecture and allow PC to initiate some very complex multiserver transaction from the desktop. 125 :: What is meant by Transparency?Transparency really means hiding the network and its servers from the users and even the application programmers.  126 :: What are Triggers and Rules?Triggers are special user defined actions usually in the form of stored procedures, that are automatically invoked by the server based on data related events. It can perform complex actions and can use the full power of procedural languages.A rule is a special type of trigger that is used to perform simple checks on data. 127 :: What are all the Extended services provided by the OS?Ubiquitous communicationsNetwork OS extensionBinary large objects (BLOBs)Global directories and Network yellow pagesAuthentication and Authorization servicesSystem managementNetwork timeDatabase and transaction servicesInternet servicesObject- oriented services 128 :: What are the most typical functional units of the Client/Server applications?

User interfaceBusiness Logic andShared data. 129 :: What is a Database Server?With a database server, the client passes SQL requests as messages to the database server. The results of each SQL command are returned over the network. The server uses its own processing power to find the request data instead of passing all the records back to the client and then getting it find its own data. The result is a much more efficient use of distributed processing power. It is also known as SQL engine.130 :: What is a Transaction server?With a transaction server, the client invokes remote procedures that reside on the server with an SQL database engine. These remote procedures on the server execute a group of SQL statements. The network exchange consists of a single request/reply message. The SQL statements either all succeed or fail as a unit.131 :: What is an Object server?With an object server, the Client/Server application is written as a set of communicating objects. Client object communicate with server objects using an Object Request Broker (ORB). The client invokes a method on a remote object. The ORB locates an instance of that object server class, invokes the requested method and returns the results to the client object. Server objects must provide support for concurrency and sharing. The ORB brings it all together.

Active Directory Questions and Answers: 1 :: Explain Active Directory schema? The Active Directory schema is the set of definitions that defines the kinds of objects, and thetypes of information about those objects, that can be stored in Active Directory. Thedefinitions are themselves stored as objects so that Active Directory can manage the schemaobjects with the same object management operations used for managing the rest of theobjects in the directory.There are two types of definitions in the schema: attributes and classes. Attributes andclasses are also referred to as schema objects or metadata.Attributes are defined separately from classes. Each attribute is defined only once and can beused in multiple classes. For example, the Description attribute is used in many classes, but isdefined once in the schema, assuring consistency. 2 :: How will you verify whether the AD installation is proper? 1. Verify SRV Resource RecordsAfter AD is installed, the DC will register SRV records in DNS when it restarts. We cancheck this using DNS MMC or nslookup command.Using MMCIf the SRV records are registered, the following folders will be there in the domainfolder in Forward Lookup Zone.

? msdes? sites? tcp? adp

Using nslookup>nslookup>ls -t SRV Domain

If the SRV records are properly created, they will be listed.

2. Verifying SYSVOLIf SYSVOL folder is not properly created data stores in SYSVOL such are scripts, GPO,etc will not be replicated between DCs.First verify the following folder structure is created in SYSVOLDomainStagingStaging areasSysvolThen verify necessary shares are created.>net shareIt should show two shares, NETLOGON and SYSVOL

3. Verifying Database and Log filesMake sure that the following files are there at %systemroot%\ntdsNtds.dit, Edb.*, Res*.log 3 :: Minimum Requirement for Installing AD? 1. Windows Server, Advanced Server, Datacenter Server2. Minimum Disk space of 200MB for AD and 50MB for log files3. NTFS partition4. TCP/IP Installed and Configured to use DNS5. Administrative privilege for creating a domain in existing network 4 :: What is LDAP? LDAP is the directory service protocol that is used to query and update AD. LDAP namingpaths are used to access AD objects and include the following:? Distinguished names? Relative Distinguished names 5 :: What is Native Mode?When all the domain controllers in a given domain are running Windows 2000 Server. This mode allows organizations to take advantage of new Active Directory features such as Universal groups, nested group membership, and inter-domain group membership.6 :: What is Mixed Mode?Allows domain controllers running both Windows 2000 and earlier versions of Windows NT to co-exist in the domain. In mixed mode, the domain features from previous versions of Windows NT Server are still enabled, while some Windows 2000 features are disabled. Windows 2000 Server domains are installed in mixed mode by default. In mixed mode the domain may have Windows NT 4.0 backup domain controllers present. Nested groups are not supported in mixed mode.7 :: What is Empty Root Domain?The "empty root domain" is an AD design element that has become increasingly popular at organizations with decentralized IT authority such as universities.

The empty root domain acts as a placeholder for the root of Active Directory, and does not typically contain any users or resources that are not required to fulfill this roll [sic]. [...] Only those privileges that have tree or forest-wide scope are restricted to the empty root domain administrators. Departmental administrators can work independently of other departments.

This politically neutral root domain provides a central source of authority and policy enforcement, and provides a single schema and global catalog that allows users to find resources anywhere in the university/district/state system. Individual IT departments retain a significant degree of

independence and can control their own users and resources without having to worry that actions by administrators in other departments will disrupt their domain.8 :: What is the Group Policy?Group Policy is one of the most exciting -- and potentially complex -- mechanisms that the Active Directory enables. Group policy allows a bundle of system and user settings (called a "Group Policy Object" or GPO) to be created by an administrator of a domain or OU and have it automatically pushed down to designated systems.

Group Policy can control everything from user interface settings such as screen background images to deep control settings in the client such as its TCP/IP configuration and authentication settings. There are currently over 500 controllable settings. Microsoft has provided some templates as well to provide a starting point for creating policy objects.

A significant advantage of group policy over the old NT-style policies is that the changes they make are reversed when the policy no longer applies to a system. In NT 4, once a policy was applied to a system, removing that policy did not by itself roll back the settings that it imposed on the client. With Windows 2000, when a specified policy no longer applies to a system it will revert to its previous state without administrative interference.

Multiple policies from different sources can be applied to the same object. For example, a domain might have one or more domain-wide policies that apply to all systems in the domain. Below that, systems in an OU can also have policy objects applied to it, and the OU can even be further divided into sub-OU's with their own policies.

This can create a very complex web of settings so administrators must be very careful when creating these multiple layers of policy to make sure the end result -- which is the union of all of the applicable policies with the "closest" policy taking priority in most cases -- is correct for that system. In addition, because Group policy is checked and applied during the system boot process for machine settings and again during logon for user settings, it is recommended that GPO's be applied to a computer from no more than five "layers" in the AD to keep reboot and/or login times from becoming unacceptably long.9 :: What is Organizational Units?OU's have many of the attributes of an NT 4 domain. However, instead of requiring server resources to create and support, they are a logical construct within the Active Directory so an OU does not have to support and maintain a domain controller.

OU's are created by an administrator of an AD domain and can be freely named (and renamed). The OU can then be populated objects of many types including computers, groups, printers, users and other sub-OU's.

The real power of an OU is that once it is established, the administrator of its "parent" can delegate administrative authority -- in total or in part -- to any user or group that is in the AD.

When this happens, the designated user/group gains complete administrative authority over all objects in their OU and thus has all of the rights and abilities that a Windows NT domain administrator would have as well as some new ones such as the ability to further segment their OU into sub-OU's and delegate authority over those sub-elements as they see fit.10 :: What is Domains in Active Directory?In Windows 2000, a domain defines both an administrative boundary and a security boundary for a collection of objects that are relevant to a specific group of users on a network. A domain is an administrative boundary because administrative privileges do not extend to other domains. It is a security boundary because each domain has a security policy that extends to all security

accounts within the domain. Active Directory stores information about objects in one or more domains.

Domains can be organized into parent-child relationships to form a hierarchy. A parent domain is the domain directly superior in the hierarchy to one or more subordinate, or child, domains. A child domain also can be the parent of one or more child domains, as shown below.11 :: What is Forest?The term "forest" is used to describe a collection of AD domains that share a single schema for the AD. All DC's in the forest share this schema and it is replicated in a hierarchical fashion among them. The preferred model for Windows 2000 AD is to have an organization use a single forest that spans an entire enterprise.

While not an administrative block by themselves, forests are a major boundary in that only limited communication is available between forests. For example, it is difficult for a user in one forest to access a resource in another forest.

It is very difficult to integrate forests at this time because of potential problems reconciling schema differences between two forests.12 :: Explain Active Directory?"Active Directory is the directory service used in Windows 2000 Server and is the foundation of Windows 2000 distributed networks."

The core of Active Directory is a combination of an LDAP server and MIT Kerberos 5 KDC running on a Windows 2000 server acting as a domain controller that work as a unit to provide authentication ("Who are you?") and authorization ("What are you allowed to do?") information within a group of interlinked systems.

Above and beyond that, the LDAP "face" of this structure behaves as an enterprise-wide distributed database that not only contains Windows-specific information but can be extended to incorporate user-defined data as well.

The AD is held together by DNS, which is used not only to locate specific machines within the AD but also to locate which functions of the AD are running on which domain controllers.

CCNA Security Questions and Answers: 1 :: Configuring ACLs is an important part of working with the IOS Firewall. What wildcard masks are replaced in ACLs by the words host and any? We have the option of using the word host to represent a wildcard mask of 0.0.0.0.Consider a configuration where only packets from IP source 10.1.1.1 should be allowed and all other packets denied. The following ACLs both do that.

R3#conf tR3(config)#access-list 6 permit 10.1.1.1 0.0.0.0R3(config)#conf tR3(config)#access-list 7 permit host 10.1.1.1

The keyword any can be used to represent a wildcard mask of 255.255.255.255. Both of the following lines permit all traffic.

R3(config)#access-list 15 permit any

R3(config)#access-list 15 permit 0.0.0.0 255.255.255.255

There?s no ?right? or ?wrong? decision to make when you?re configuring ACLs in the real world. For your exam, though, I?d be very familiar with the proper use of host and any. 2 :: Identify the true statements regarding the Authentication Proxy A. It?s part of the IOS Firewall Feature Set.B. It allows creation of per-user security profiles, rather than more general profiles.

C. It allows creation of general security profiles, but not per-user profiles. D. Profiles can be stored locally, but not remotely.E. Profiles can be stored on a RADIUS server.

F. Profiles can be stored on a TACACS+ server.

Ans: (A, B, E, F. T he Authentication Proxy allows us to create security profiles that will be applied on a per-user basis, rather than a per-subnet or per-address basis. These profiles can be kepton either of the following:

? RADIUS server? TACACS+ server

Upon successful authentication, that particular user?s security policy is downloaded from theRADIUS or TACACS+ server and applied by the IOS Firewall router. 3 :: Which of the following are considered parts of the IOS Firewall feature set? A. IOS FirewallB. Intrusion Prevention System

C. RADIUS

D. Authentication Proxy

E. Password Encryption

Ans:(A, B, D.) There are three major components to the IOS Firewall feature set - the IOSFirewall, the Intrusion Prevention System (IPS), and the Authentication Proxy. 4 :: Does the Cisco IOS Firewall feature set act as a stateful or stateless packet filter? The Cisco IOS Firewall is a stateful filter. 5 :: Identify the true statements in below A. Stateless packet filtering considers the TCP connection state. B. Stateful packet filtering considers the TCP connection state.C. Neither stateless nor stateful packet filtering monitor the TCP connection state.

D. Both stateless and stateful packet filtering monitor the TCP connection state, and keep a state table containing that information.

Ans: (B.) Stateful packet filtering does monitor the connection state, and that?s particularly important when it comes to preventing TCP attacks. A stateful firewall will not only monitor the state of the TCP connection, but also the sequence numbers. Stateful firewalls accomplish this by keeping a session table, or state table.

 6 :: Define the term ?DMZ? as it pertains to network security, and name three different common network devices that are typically found there?It?s easy to think of your network as the ?inside?, and everything else as ?outside?. However, we?ve got a third area when it comes to firewalls - the DMZ.

From an IT standpoint, the DMZ is the part of our network that is exposed to outside networks. It?s common to find the following devices in a DMZ:

? FTP server? Email server? E-commerce server? DNS servers? Web servers

CCNP Questions and Answers:

1 :: Explain the function of a rendezvous point? A RP is the focal point for multicast traffic. Traffic is forwarded to the RP from multicast sources. The RP then forwards traffic to multicast receivers. 2 :: What is the purpose of the interface command ip multicast spares-dense-mode? Used with PIMSM Auto-RP and version 2. If the RPs fail, the router reverts to dense mode. 3 :: What is the range of IP multicast addresses? 224.0.0.0-239.255.255.255 4 :: Describe the operation of Anycast RP. Two or more RPs are configured with the same IP address. The IP addresses of the RPs are advertised using a unicast IP routing protocol. Each multicast router chooses the closest RP. If an RP fails, the routers switch to the next nearest RP after the unicast IP routing protocol converges. The MSDP is used between RPs to exchange active multicast source information. 5 :: What protocols do switches use to prevent the broadcasting of multicast traffic? CGMP and IGMP Snooping  6 :: Why are the Cisco multicast routing protocols referred to as protocol independent?Multicast forwarding decisions are based on the entries in the unicast IP routing table. Multicast is not dependent on how the unicast IP routing table was built; you can use any dynamic interior routing protocol, static routes, or a combination of the two.7 :: Determine at least four IP multicast groups that have the multicast Ethernet address of 01 00 5E 00 40 0C?The low order 32 bits of the IP address determine the multicast Ethernet address. The first four bits are always 1 1 1 0 and the next five bits can be anything. Therefore, the IP multicast addresses that map to the multicast Ethernet address of 01 00 5E 00 40 0C are

1110 0000 0000 0000 0100 0000 1100 = 224.0.64.12

1110 0000 1000 0000 0100 0000 1100 = 224.128.64.12

1110 0001 0000 0000 0100 0000 1100 = 225.0.64.128 :: What is the multicast Ethernet address for IP address 227.128.64.12?

The base Ethernet multicast address is 01 00 5E 00 00 00. The first byte of the IP multicast address is not used. If the second byte is greater than 127, subtract 128, giving a value of 0. The third and fourth bytes of the IP address are used as is after converting to hex. Their values, in hexadecimal, are 40 and 0C. So the Ethernet multicast address for the IP multicast address 227.128.64.12 is 01 00 5E 00 40 0C.9 :: Explain the difference between dense mode and sparse mode multicast.Dense mode multicast assumes all multicast neighbors want to receive all multicast traffic unless the neighbors have specifically pruned the traffic. Sparse mode multicast assumes multicast neighbors do not want to receive multicast traffic unless they have asked for it. Dense mode uses source-based delivery trees while sparse mode uses shared delivery trees where traffic is first sent to an RP.10 :: Explain the difference between the forwarding of a unicast IP packet and the forwarding of a multicast IP packet.Unicast IP packets are forwarded based on the destination IP address. Multicast packets are forward based on the source IP address. If a multicast packet is received on the interface used to send a unicast packet back to the source, the multicast packet is forwarded to multicast neighbors. If the multicast packet is received on an interface that would not be used to send a unicast IP packet back to the source, the packet is discarded. 11 :: What are the four general types of BGP attributes?Well-known mandatory, well-known discretionary, optional transitive, and optional nontransitive.12 :: Why is BGP a better choice for Internet routing than the IGPs?RIP version 1 and IGRP are classful protocols and do not advertise subnet mask information. RIP version 2 has a limited network diameter of 15 hops. EIGRP, OSPF, and IS-IS use computational intensive algorithms for determining a shortest path. BGP relies on simple techniques for best path selection and loop detection, and can handle the number of network prefixes required for Internet routing.13 :: What is the major difference between BGP and IGP route summarization?When a summary address is created with an IGP (EIGRP, OSPF, and IS-IS), the specific routes of the summary are not advertised. BGP advertises the summary, and all the specific routes of the summary unless they are specifically suppressed.14 :: Why does IBGP require a full mesh?BGP uses the AS_PATH attribute for loop detection. If a router sees its own AS number in a BGP advertisement, the advertisement is dropped. IBGP routers have the same AS number so the AS number cannot be used for loop detection. IBGP neighbors will not advertise prefixes learned from one IBGP neighbor to another IBGP neighbor; therefore, a full mesh is required.15 :: Name two methods for reducing the number of IBGP connections.Route reflector and confederation. 16 :: What is synchronization?Synchronization is a property of IBGP. An IBGP router will not accept a prefix received from an IBGP neighbor if the prefix is not already in the IP routing table.17 :: What is the first thing that BGP checks to determine if a prefix is accessible?BGP checks the NEXT_HOP attribute to determine if the NEXT_HOP is accessible or in the IP routing table.18 :: Name all the ways for installing a prefix in the BGP routing table.► Using the network command to transfer a router from the IP routing table to the BGP routing table

► Redistributing routes from the IP routing table to the BGP routing table

► Learned from a BGP neighbor19 :: What is the order of preference for the BGP attributes AS_PATH, LOCAL_PREF, MED, and WEIGHT?WEIGHT, LOACL_PREF, AS_PATH, MED20 :: What is the purpose of the metric or MULTI_EXIT_DISC attribute?MED is used to prefer a path into an autonomous system. A lower MED value is preferred.What is crosstalk? Crosstalk refers to the interference between channels. In the xDSL world, the interference between nearby cables can have a negative impact on the performance of the affected cable(s). Have you ever been on the phone and heard some other conversation, not yours, in the background? If so, you have experienced the effect of crosstalk.

Near-end crosstalk (NEXT) occurs when the transmitter sends a signal and a nearby transceiver at the same end of link, through capacitive and inductive coupling, "hears" the signal.

Far-end crosstalk (FEXT) occurs when the transmitter sends a signal and a transceiver at the far end of the link, through capacitive and inductive coupling, "hears" the signal. FEXT will be of more concern in an asymmetrical system such as ADSL than symmetrical systems like HDSL. This is because strong signals originating from the near end, can interfere with the weaker signals originating at the far end.Explain Asynchronous vs. Synchronous Transmission?Serialized data is not generally sent at a uniform rate through a channel. Instead, there is usually a burst of regularly spaced binary data bits followed by a pause, after which the data flow resumes. Packets of binary data are sent in this manner, possibly with variable-length pauses between packets, until the message has been fully transmitted. In order for the receiving end to know the proper moment to read individual binary bits from the channel, it must know exactly when a packet begins and how much time elapses between bits. When this timing information is known, the receiver is said to be synchronized with the transmitter, and accurate data transfer becomes possible. Failure to remain synchronized throughout a transmission will cause data to be corrupted or lost.

Two basic techniques are employed to ensure correct synchronization. In synchronous systems, separate channels are used to transmit data and timing information. The timing channel transmits clock pulses to the receiver. Upon receipt of a clock pulse, the receiver reads the data channel and latches the bit value found on the channel at that moment. The data channel is not read again until the next clock pulse arrives. Because the transmitter originates both the data and the timing pulses, the receiver will read the data channel only when told to do so by the transmitter (via the clock pulse), and synchronization is guaranteed.