ccna interview preparation 1

8/6/2019 Ccna Interview Preparation 1

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CCNA

WRITTEN TEST Question Paper

1. What is Subnetting and its uses?

2. Differentiate between Routing Protocol and Routed Protocol , give some examples

for both.

Routing Protocols: the routing protocol is the protocol used to send update between the routersabout the networks that exist in the organization.

Example: RIP,OSPF,IS-IS,IGRP,EIGRP

OR: is used by routers to dynamically find all the network in the internetwork & make sure that all routers

have the same routing tables.

Routed Protocols : Once all the routers knows about all the networks a routed protocol can beused to send user data through the internetwork

Example: IP, IPX

3. Mention the use of IP Subnet- zero commands.

4. How will you find the number of IP addresses and number of host in the given IP

Subnet? 172.168.100.0126

5. Mention about RIP protocol and its timers and its use of timers?

RIP Timers

Route Update Timer- The routing-update timer clocks the interval between periodic routingupdates. It is usually set to 30 seconds.

Route Invalid TImer- The Route Invalid Timer determines the length of time (90 seconds)before a route is considered invalid. If it doesn't receive an update for the route it sets the routeas invalid and notifies its neighbors.

Route Flush Timer- The Route Flush Timer sets the time between when a route becomesinvalid and its removal from the routing table (240 seconds). Time must be longer than invalidtimer so it can tell its neighbors about the route.

6. Mention about Io1 rp protocol and its timers.


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7. Differentiate between RIP1 & RIP2

8. What is the Administrative distance (AD) value for RIP,IGRP,OSPF,BIGRP

Route Source Default Administrative Distance

Connected Interface 0

Static Route 1

EIGRP summary route 5

EIGRP 90

External EIGRP 170IGRP 100

OSPF 110

RIP 120

IS-IS 115

EGP 140

External BGP 20

Internal BGP 200

Unknown 255 (this route will never be used)

9. Mention the use of AD

Administrative Distance (AD): is used to rate the trustworthiness of routing informationreceived on a router from a neighbor router. An administrative Distance is an integer from 0 to 255,where 0

is the most trusted and 255 means no traffic will be passed via this route

10. How does IP communicate between two nodes shown in the figure.


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11. Mention the use of show IP Interface

This command enables you to see IP configuration of your router interface

12. How ISDN works and how to configure on router?

ISDN is actually a set of communication protocols proposed by telephone companiesthat allow them to carry a group of digital services that simultaneously convey data,text, voice,music, graphics, and video to end users, and it was designed to achievethis over the telephone systems already in place.

These are the benefits of ISDN:1)It can carry voice, video, and data simultaneously.2)Call setup is faster than with an analog modem.3)Data rates are faster than on an analog modem connection.4) ISDN offers Dial on Demand Routing, which means you only pay for the time thatyou use the link.5)Small office and home office sites can be economically supported with ISDN BRIservices.6)ISDN can be used as a backup service for a leased-line connection between theremote and central offices.7)ISDN provides a faster data transfer rate than modems by using the B channel.When multiple B channels are used, ISDN offer users more bandwidth on WANs.

13. Mention about PRI & BRI interfaces and its value

Basic Rate Interface (BRI)

ISDN Basic Rate Interface (BRI) service, also known as 2B+D, provides two Bchannels and one D channel. The BRI B-channel service operates at 64Kbps andcarries data, while the BRI D-channel service operates at 16Kbps and usually carriescontrol and signaling information. The total bandwidth for ISDN BRI is then 144Kbps(64 + 64 + 16 = 144).The D channel carries signaling information to setup and control calls.

Primary Rate Interface (PRI)ISDN Primary Rate Interface (PRI) servicealso known as 23B+Ddelivers 23 64KbpsB channels and one 64Kbps D channel, for a total bit rate of 1.544Mbps.

14. Mention about the use of ISDN switch type command

15. Mention the use of Dialer list command


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Dial-on-Demand Routing (DDR)

Dial-on-demand routing (DDR) is used to reduce WAN costs if you have to pay on a per-minute or per-

packet basis.DDR works when a packet received on an interface

1. The route to the destination network is determined to be across the dial-up connection.

2. Interesting packets dictate a DDR call.3. Dialer information is looked up and the call is placed.

4. Traffic is transmitted.

5. Call is terminated when no more interesting traffic is being transmitted over a link and the idle-timeout

period ends.

Configuring DDR

1. Define static routes, which specify how to get to the remote networks and whatinterface to use to get there.2. Specify the traffic that is considered interesting to the router.3. Configure the dialer information that will be used to dial the interface to get to theremote network.

Configuring Static RoutesRouterA(config)#ip route 172.16.50.0 255.255.255.0172.16.60.2RouterA(config)#ip route 172.16.60.2 255.255.255.255 bri0

What this does is tell the router how to get to network 172.16.50.0 through172.16.60.2.

The second line tells the router how to get to 172.16.60.2. This second IP routecommand is vital, as youll soon see; together with the dialer map command, it letsISDN know where to place the call.

16. What is Access list? Mention about the types

17. What is the use of SNMP protocol?

Simple Network Management Protocol.

The SNMP protocol is used by network management systems to communicate with

network elements.

The Simple Network Management Protocol (SNMP) is essentially a request-reply

protocol running over UDP (ports 161 and 162)


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18. What is VLAN?

What is VLAN: Creating Multiple virtual LANs across the switch is called as VLAN

19. Differentiate between Trunk line & Access Line

Access Link: Access link is a link that is part of only one Vlan,which is referred to as the native Vlan of

the port.Trunk Link : Trunk can carry multiple VLAN information across the switch. A trunk is used to connect

switches to other switches, or routers. Trunk links are supported on fastEthernet or Gigabit Ethernet only

20. What is supernetting?

Combining several IP network addresses into one IP address. Supernetting

reduces the number of entries in a routing table and is done in CIDR

addressing as well as internal networks.

21. What is leased lines? How it works?

Typically, these are referred to as apoint-to-point connection or dedicatedconnection.Which has been leased for private use. In some contexts, it's called a dedicated line.

22. How does trace route work?

Traceroute is the program that shows you the route over the network between two

systems, listing all the intermediate routers a connection must pass through to get to its

destination. It can help you determine why your connections to a given server might bepoor, and can often help you figure out where exactly the problem is. It also shows you

how systems are connected to each other, letting you see how your ISP connects to the

Internet as well as how the target system is connected.

23. Differentiate Straight Cable and Cross Cable


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24. Differentiate between Hub and Switches

25. Following in an illustration of two connected routers.R1 & R2 are 2 routers which

are connected by 2MBPS leased line and 128 KBPS ISDN, if there is failure of

2MBPS Leased line during transmission , then transmission should be taken over

by128KBPS How do you configure this condition?

26. What is subnetting?

27. Given a network e.g:172.16.23.0/20, how many sub networks are possible? and

what is the next subnet address after the zero subnet?

28.

a) Given a mesh kind of connection to 4-5 switches, how can you find the root bridge

and root port, which port will be in forward state and blocking state?

b) Please prepare the STP part, very important.

29. Which is better OSPF or EIGRP?

OSPF EIGRP


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Supports CIDR and VLSM, rapid

convergence, partial updates, neighbordiscovery

Supports CIDR and VLSM, rapid

convergence, partial updates, neighbordiscovery

Administrator can define route

summarization

Automatic route-summarization and user-

defined route summaries

Open standard; multivendor support Proprietary; Cisco routers only

Scalable; administratively defined

areas provide manageable hierarchy

Scalable, but no hierarchical design

Difficult to implement

Equal-cost load balancing

Easy to implement

Unequal-cost load balancing

30. What are the features of OSPF or EIGRP?

Features of EIGRP

Great for scaling current EIGRPReduction of dandthwidth

Route summarizationRoute redistribution

Dual Algorithm= Fast convergence

EIGRP user incremental update

Function in LAN & WAN

Supports VLSL: suppernetting

Metric based on Bandwidth/Delay

Load balance up to 6 equal & unequal paths

Provides support for multiple protocolsEasy to configure

Backward compatible with IGRP

OSPF Features


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Fast convergence: Whenever there is change in topology, it will send onlyTriggered updates.

It supports unlimited size:

Less bandth utilization

It user Dikjestra Algorithm to calculate best path to the destination

Cost will be calculate based on Bandth/Delay 10*8/Bandth-width

31. What are the features of distance vector?

Distance Vector Link-State

Sends its entire routing table at periodicintervals out of all interfaces (typically,this is based in seconds). It will also sendtriggered updates to reflect changes inthe network.

Sends incremental updates when achange isdetected.

RIP, IGRP, EIGRP ( Hybbid) OSPF, IS-ISTypically involves updates sent using abroadcast address to everyone on thelink.

Typically involves updates sent to thoserouters participating in the routingprotocol domain, via a multicast address.

Uses a metric based on how distant theremotenetwork is to the router. (IGRP does notconform to this as a proprietary solution.)

Is capable of using a complex metric

Has knowledge of the network based oninformation learned from its neighbors.

Has knowledge of the network based oninformation learned from every router inthe area.

Includes a routing table that is adatabase viewed from the perspective ofeach router.

Has a topological database that is thesame forevery router in the area. The routingtable that is built from this database isunique to each router.

Uses Bellman Ford algorithm for Uses the Dijkstra algorithm.


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calculating thebest path.Does not consume many routerresources, but is heavy in the use ofnetwork resources.

Uses many router resources, but isrelatively low in its demand for networkresources.

Maintains one domain in which all the

routes are known.

Has a hierarchical design of areas that

allow forsummarization and growth.Involves slower convergence becauseinformation of changes must come fromthe entire network (but indirectly). Eachrouting table on every intervening routermust be updated before the changesreach the remote end of the network.

Involves quicker convergence becausethe update is flooded immediatelythroughout the network.

32. How to check connectivity Ping and Trace route?

Trace route : Trace can be used to show the path a packet takes through theinternetwork to a remote host.

Ping:You can use ping to test network connectivity and test name resolution.

33. How does IP packet Flow?

34.What is ISDN? Mention the use of ISDN

35.What is leased line Configuration? How it works?

.

36. What is AD ? Mention AD for different protocols

37. Mention about the lease Line Components

38.What is the output of Show Interface and show version?

39.What is HDLC and PPP Authentication?

HDLC is the default encapsulation used by Cisco routers over synchronous serial links. HDLC is a

point-to-point protocol used on leased lines between Cisco devices & No authentication can be used

with HDLC. Its a data link layer protocol.

PPP AuthenticationYou have two methods to choose from to implement authentication:

PPP Authentication Protocol (PAP)


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Challenge Handshake Authentication Protocol (CHAP).

The authentication process is performed before the network and data link layerprotocols are negotiated for the PPP connection by NCP. If the authentication fails,then the serial data link connection will not come up. Authentication is optional andadds very little overhead to the connection.

PAP (PPP Authentication Protocol )

PAP is the simplest, but the least secure. During the authentication phase, PAP goesthrough a two-way handshake process. In this process, the source sends itsusername (or hostname) and password, in clear text, to the destination. Thedestination compares this information with a list of locally stored usernames andpasswords. If it finds a match, the destination sends back an acceptmessage.If itdoesnt find a match, it sends back a rejectmessage.PAP authentication process.

CHAP (Challenge Handshake Authentication Protocol )

Note: One big problem with PAP is that it sends the username and password acrosstheWAN connection in clear text. If someone is tapping into the WAN connection andeavesdropping on the PPP communication, theyll see the actual password that isbeingused. In other words, PAP is not a secure method of authentication.

CHAP, on the other hand, uses a one-way hash function based on the MessageDigest 5 (MD5) hashing algorithm to hash the password. This hashed value is thensent across the wire. In this situation, the actual password is never sent. Anyonetapping the wire will not be able to reverse the hash to come up with the originalpassword. This is why MD5 is referred to as a one-way functionit cannot be

reverseengineered.

CHAP uses a three-way handshake process to perform the authentication. First, thesourcesends its username (not its password) to the destination. The destination sends backa challenge, which is a random value generated by the destination.

The default encapsulation on Ciscos synchronous serial interfaces isHDLC

40.What is Vlan? Mention its types and basics.

What is VLAN: Creating Multiple virtual LANs across the switch is called as VLAN

Based on VLAN boundaries

1) End-to-End VLANs: VLANs are configured to allow membership based on

function,project,department and so on..


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Best feature of End-to-End VLANs is that users can be placed in a VLAN regardless of their

physical location.The administrator defines the port the user is connected to as a VALN member.

If user moves, the administrator defines their new port as a member of exiting VLAN

2) Local VLAN : Local VALN is configured by physical location and not by

function,project,department and so on. Local vlans are user in corporations that have centralizedservers.

Based on Members

1) Static VALN: Administrator Creates a VLAN and then assigns switch ports to it.The association

does not change until the administrator changes the port settings.

2) Dynamic VLAN: A dynamic VLAN will tell the switch port, which VLAN it belongs to,based

on the mac address of the device that connects to the port.

Dynamic VLAN will be configure by usingVLAN Management Police Server( VMPS)

It is a service to set up a database of MAC address that can be user for dynamic addressing of

VLAN.VMPS is a MAC-address-to-VLAN mapping database.

41.Mention about basic switching operation

42. Differentiate between broadcast, multicastand unicast.

43.What is STP and functionality of STP ?

STP is used to Prevent Layer 2 loops & Provide Redundancy

Electing a Root Bridge

Root Bridge: is one which runs Spanning tree protocol in layer 2 N/W

OR: The root bridge is the bridge with the best Bridge ID

The Root Bridge is chosen by an election process among all connectedswitches. Each switchhas a unique Bridge IDthat it uses to identify itself to other switches. TheBridge ID is an8-byte value that is made up of the following fields: Bridge Priority (2 bytes)The priority or weight of a switch in relation toall otherswitches. The priority field can have a value of 0 to 65,535 and defaults to32,768 MAC Address (6 bytes)The MAC address used to determine which isthe lowest ID

NotePort Cost: When a BPDU sent out a switch port, the BPDU is assigned a portcost

Path Cost: is the some of all the port costs,

Selecting Root Port

Root port: one which is very close to the Route Bridge & receives best BPDU


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OR: The link directly connected to the root bridge, or the shortest path to the root bridge.If more than one

link connects to the root bridge,then a port cost is determined by checking the bandwidth of each link.The

lower cost port becomes the root port.

44.Mention about Loops and Redundency

45.Mention about basic of multilayer Switching

46.Mention about HSRP and VRRP basic concepts

47.Discuss on IP subnet zero and IP classless.

48) What is full form of PING ?

ANS: Packet Internet Groper

49) In which layer the PING & Trace route works?

ANS: Network layer

50) What is default setting for UDLD?

UniDirectional Link Detection

UDLD is a Layer 2 protocol that enables devices connected through fiber-optic or

twisted-pair Ethernet cables to monitor the physical configuration of the cables and detectwhen a unidirectional link exists. All connected devices must support UDLD for the

protocol to successfully identify and disable unidirectional links. When UDLD detects a

unidirectional link, it disables the affected port and alerts you. Unidirectional links can

cause a variety of problems, including spanning-tree topology loops

51) What are the types of L2 switching?

Cut Through - fastest switching mode as only the destination address is copied. It will

then look up the address in its filter table and send the frame to the appropriate interface.

Store and Forward - the entire frame is copied into its buffer and checks for CyclicRedundancy Check (CRC). The frame is discarded if it contains a CRC error or if it is a


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runt (less than 64 bytes) If the frame does not contain any errors, the LAN switch looks

up the destination address in its forwarding, or switching, table and determines the

outgoing interface.

Fragment Free - The switch waits for the first 64 bytes to pass before forwarding the

frame. If the packet has an error, it usually occurs in the first 64 bytes of the frame.

Default mode for 1900 switches.

52) TCP & UDP works @ which OSI Layer?

52) How to find DCE & DTE interface in serial connection

A Cisco router is a DTE by default, but directly connecting two DTEs with a DCE/DTE

cable is not enough. In the following example, R1 and R3 are directly connected at theirSerial1 interfaces. The line goes up briefly after being opened, but the line protocol goes

down after about 30 seconds.

2d18h: %LINK-3-UPDOWN: Interface Serial1, changed state to up

2d18h: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1, changed state todown

The problem is that one of the routers needs to act as the DCE in order for the line

protocol to come up and stay up. You could just go over and look at the DTE/DCE cableto see which router had the DCE end of the cable attached. OR the Female interface is the

DCE interface. In this example, though, we don't have physical access to the routers.

How can we tell which router has the DCE end of the cable attached?

R3#show controller serial 1

HD unit 1, idb = 0x1C44E8, driver structure at 0x1CBAC8

buffer size 1524 HD unit 1, V.35 DCE cable

The router with the DCE end of the cable needs to supply a clock rate to the DTE, and

we'll do just that with the interface-level clockrate command.


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R3#conf t

Enter configuration commands, one per line. End with CNTL/Z.

R3(config)#int serial1

R3(config-if)#clockrate 56000

1. introduce yourself?

2. hub & switch

3. collisin & broad cast domain

4. routing & routed protocols

5. explain the difference between EIGRP & ospf6. types of wan connection

7. explain frame-rely

8. problem on subnetting

9. vlan,wat is the need 4 it

10.vtp

VTP VLAN Trunk Protocol.

Benefits of VTP

VTP Modes of OperationsTo participate in a VTP management domain, each switch must be configuredto operate in oneof several modes. The VTP mode will determine how the switch processesand advertises VTPinformation. The following modes can be used:

Server modeVTP servers have full control over VLAN creation andmodification for


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their domains. All VTP information is advertised to other switches in thedomain, whileall received VTP information is synchronized with the other switches. Bydefault, a switchis in VTP server mode. Note that each VTP domain must have at least oneserver so that

VLANs can be created, modified, or deleted, and so that VLAN informationcan bepropagated.

Client modeVTP clients do not allow the administrator to create, change,or delete anyVLANs. Instead, they listen to VTP advertisements from other switches andmodify theirVLAN configurations accordingly.

Transparent modeVTP transparent switches do not participate in VTPdomain, but still receive & forward VTP advertisement through the configured

trunk links.

1. How is ur day begin in ur office?wat is ur day today

activities?

2. how will u trouble shoot a leased line?

3. which is coastlier leased line or ISDN?

4. VTP/VLAN

5. wat is a non-modular and modular router?6. explain lsa types of ospf

7. wat is a auxillary port in router?

8. how u will connect a auxillary port

9. how to connect a isdn line to router

10.wat is nt1,nt2,te

11.explain ospf in detail..

12.explain how tracert is working?

13.wat is supervisor engine in l3 switch?

14.can we configure a routing protocol on a 2950 switch?

why?

15.wat is stp?different port status of stp?

STP Port States


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STP Default Timers

1) What is your day 2-day activity

2) What is VLAN? How u will configure? In both Cat & IOS based config.

3) How to enable Ethernet port to the VLAN.

4) What is the default cost for OSPF?

5) Whats the command to see logs in the Cisco devices

6) Whats the command to see the neighbors?

7) Whats the command to see VLAN configuration?

8) Whats the command to see the interface details?

1) What is your role in present working company

2) Is the single port can be a part of 2 VLAN & how u will configure it


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3) What is auxiliaryvlan? How u will configure

4) Whats the difference between SupII & SupIV engine.

5)

1) Tell me something about working profile

2) How u will upgrade the IOS in WAN links

3) If the link between Bangalore to Mumbai is not working, how u will analyze?

4) What is Floating static route?

1) How u will say EIGRP is fast convergence2) If u have internal network why u want authentication in OSPF

3) What is FD & AD in EIGRP. How it calculates.

4) In a WAN Link if both Serial & line protocol is down...How u will troubleshoot5) whats the difference between stub area & not so stubby area ? Why we need this.

6) Why totally stub area blocks LSA-3,4,5....whats the use.

7) What are the types of OSPF8) What are the updates u will find in topology table in EIGRP

9) How u will conveince which protocol is good for the network

10) Once the neighbour relationship is established in OSPF, what is the next step?11) What is LSA 7 ? Why is changes to LSA-5 in ABR12) What is native VLAN?

13) Why u will create a VLAN in a switch

14) Why u want spanning tree?

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