nplab viva questions

7/30/2019 Nplab Viva Questions

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CRACKED BY 123ARENA.COMPort numbers

16 bit

FTP 20 OR 21

22: Secure Shell (SSH)

23: Telnet protocolunencrypted text communications, remote login service

25: Simple Mail Transfer Protocol (SMTP)used for e-mail routing between mail servers

80: Hypertext Transfer protocol (HTTP)

110:Post Office Protocol v3 (POP3) 110

Domain Name System 53

DHCP 67, 68

143: Internet Message Access protocol IMP4

161: Simple Network management Protocol SNMP

LDAP Llight weight Directory Access Protocol 389

443: HTTP Secure HTTPS

Well known ports 0 to 1023

Registered ports 1024 to 49151IP address size 32 bit

difference between broadcasting and muti casting

Network interface cards r usually programmed to listen for three types of messages. They r

messages sent to their specific address, messages broadcast to all NICs, and messages that qualify

as a multicast for the specific card. There r three types of addressing:

Unicast - A transmission to a single interface card.

Multicast - A transmission to a group of interface cards on the network.

Broadcast - A transmission to all interface cards on the network. RFC 919 and 922 describe IP

broadcast datagrams.

Limited Broadcast - Sent to all NICs on the some network segment as the source NIC. It isrepresented with the 255.255.255.255 TCP/IP address. This broadcast is not forwarded by routers so

will only appear on one network segment.

Direct broadcast - Sent to all hosts on a network. Routers may be configured to forward directed

broadcasts on large networks. For network 192.168.0.0, the broadcast is 192.168.255.255.

All other messages r filtered out by the NIC softwr unless the card is programmed to operate in

promiscuous mode to perform network sniffing.

Broadcasting

The types of broadcasting uses on TCP/IP that I know abt r:

ARP on IPDHCP on IP

Routing table updates. Broadcasts sent by routers with routing table updates to other routers.

The ethernet broadcast address in hexadecimal is FF:FF:FF:FF:FF:FF. There r several types of IP

broadcasting:

The IP limited broadcast address is 255.255.255.255. This broadcast is not forwarded by a router.

A broadcast directed to a network has a form of x.255.255.255 where x is the address of a Class A

network. This broadcast may be forwarded depending on the router program.

A broadcast sent to all subnetworks. If the broadcast is 10.1.255.255 on network 10.1.0.0 and the

network is subnetted with multiple networks 10.1.x.0, then the broadcast is a broadcast to all

subnetworks.

A broadcast sent to a subnet in the form 10.1.1.255 is a subnet broadcast if the subnet mask is
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255.255.255.0.

Multicasting

Multicasting may be used for streaming multimedia, video conferencing, shrd white boards and

more as the internet grows. Multicasting is still new to the internet and not widely supported by

routers. New routing protocols r being developed to enable multicast traffic to be routed. Some of

these routing protocols r:

TCP transmission Control protocol

ATM Asynchronous Transfer ModeARP/RARP Address Resolution Protocol / Reverse Address Resolution ProtocolDHCP Dynamic Host Configuration Protocol (TCP/IP)FDDI Fiber Distributed Data Interface, standardized by ANSIFTP File Transfer Protocol (TCP/IP)GSM GPRS Session ManagementHTTP Hypertext Transfer Protocol (TCP/IP)IP Internet Protocol, routing layer datagram service of the TCP/IP suiteLDAP Lightweight Directory Access Protocol

RIP Routing Information Protocol, maintains a database of network hosts and exchangeinformation about the topology of the network (XNS).

SMTP Simple Mail Transfer Protocol, mail service modeled on the FTP file transfer service(TCP/IP).

SNMP Simple Network Management Protocol, developed by the Internet community toallow diverse network objects to participate in a global network managementarchitecture.

UDP User Datagram Protocol, provides a simple but unreliable message service fortransactionoriented services (TCP/IP).

Layers in TCP/IP Model

Link Layer- protocols in this layer-ARP,NDP, PPP, media Access Control

Internet layer- protocols in this layer- IPV4, Ipv6, ICMP, IPSec

Transport layer-protocols in this layer-TCP, UDP

Aplication layer-protocols in this layer- DHCP, DNS, FTP, HTTP,POP, TELNET, IMAP, LDAP

HUB: contains multiple ports. When packet arrives at one port, it is copied unmodified to all ports

of the hub for transmission

Question: What is the difference between a router and hub or switch?

Answer: A router is a more sophisticated network device than either a switch or a hub. Like hubs

and switches, network routers are typically small, box-like pieces of equipment that multiple

computers can connect to. Each features a number of "ports" the front or back that provide the

connection points for these computers, a connection for electric power, and a number of LED lights

to display device status. While routers, hubs and switches all share similiar physical appearance,

routers differ substantially in their inner workings.

Traditional routers are designed to join multiple area networks (LANs and WANs). On the Internetor on a large corporate network, for example, routers serve as intermediate destinations for network

traffic. These routers receive TCP/IP packets, look inside each packet to identify the source and
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target IP addresses, then forward these packets as needed to ensure the data reaches its final

destination.

Routers for home networks (often called broadband routers) also can join multiple networks. These

routers are designed specifically to join the home (LAN) to the Internet (WAN) for the purpose of

Internet connection sharing. In contrast, neither hubs nor switches are capable of joining multiple

networks or sharing an Internet connection. A home network with only hubs and switches mustdesignate one computer as the gateway to the Internet, and that device must possess two network

adapters for sharing, one for the home LAN and one for the Internet WAN. With a router, all home

computers connect to the router equally, and it performs the equivalent gateway functions.

Difference difference between Bridge and Gateway?

Bridge is a interface between two or more separate collision domains (limits broadcast to devices

connected onto that port only). While Gateway is exit or entrance point to a network and performs

changes in protocols if required for e.g. DSL Broadband router connection.gateway may have

protocol translators but bridge can not

ISDN (Integrated Services Digital Network) is a set of CCITT/ITU standards for digital

transmission over ordinary telephone copper wire as well as over other media. Home and business

users who install an ISDN adapter (in place of a telephone modem) receive Web pages at up to 128

Kbps compared with the maximum 56 Kbps rate of a modem connection. ISDN requires adapters at

both ends of the transmission so your access provider also needs an ISDN adapter. ISDN is

generally available from your phone company in most urban areas in the United States and Europe.

In many areas where DSL and cable modem service are now offered, ISDN is no longer as popular

an option as it was formerly

ISDN (Integrated Services Digital Network) is a set of CCITT/ITU standards for digital

transmission over ordinary telephone copper wire as well as over other media. Home and business

users who install an ISDN adapter (in place of a telephone modem) receive Web pages at up to 128

Kbps compared with the maximum 56 Kbps rate of a modem connection. ISDN requires adapters at

both ends of the transmission so your access provider also needs an ISDN adapter. ISDN is

generally available from your phone company in most urban areas in the United States and Europe.

In many areas where DSL and cable modem service are now offered, ISDN is no longer as popular

an option as it was formerly

802 MAN

802.6 DQDB

802.3 CSMA/CD Access Method( Ethernet)802.5 Token ring Access control

802.4 token bus

803.2 Logical Link control

802.16 Wi Max

JAVA

difference between class and interface

Advantages of java

java virtual machine

Thread creationlife cycle of thred

multi threading


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difference between applet and servlet

CGI

Thread synchronization- waitand notify functions

Exception handling- list few java built in exception-try, catch finally blocks

ArithmeticException Arithmetic error, such as divide-by-zero.

ArrayIndexOutOfBoundsException Array index is out-of-bounds.

IndexOutOfBoundsException Some type of index is out-of-bounds.NegativeArraySizeException Array created with a negative size.

NullPointerException Invalid use of a null reference.

NumberFormatException Invalid conversion of a string to a numeric format.

StringIndexOutOfBounds Attempt to index outside the bounds of a string.

InterruptedException One thread has been interrupted by another thread.

NoSuchFieldException A requested field does not exist.

NoSuchMethodException A requested method does not exist

XML- Extensible Markup Language

XSL-Extensible Stylesheet Language

javabeans featuresproperties of javabeans

applet

RMI architecture

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