Computer Network Interview Questions And Answers

I have put few in my personal blog , (in my signature) can paste the same here once I reach home.

few of them can be answered like below.( not complete though)
1. Why was OSI Reference Model created? Why it is a layered model?
Prior to OSI, every compnay ( hardware/software) used their own internal standar to manufacture devices or protocols. Hence restircted the users to use one specific vendor related devices for smooth operation .OSI model kiils this dependency and brings all the vendors onto same platform. OSI took to long to standardise hence its only in papers as of now. TCP ?IP reference model is the one which is used widely.
Layering is not exactly in physical sense, layers here show the interdependecny and flow of activity .
2. Under what situations can a packet go in an infinte loop in a network?
A pakcet can go in a infinite network in a network if 1. There are incorrect routing table entries 2. a LAN is not configured with STP
It can be elimitated at L3 by introducing a parameter Time to live (TTL) and in some cases hop count
as far as in L2 , STP/RSTP can solve the problem
3. What is 'TripleX' in networks?
4. What does the mount protocol do?
5. What is meant by beaconing?
is more like keepalive messages
6. What is border gateway protocol?
When a packet needs to be routed between different service providers network border gateway routing protocol comes into picture.
7. What is the difference between ARP and RARP?
ARP - I know the IP address, whats the MAC address
When a computer needs to route the packet within a network , it does the below
> match its own IP address , subnet with that of the destinations IP address and subnet
if both of them are in same network, the computer does an ARP saying:hey! I have this IP, whose MAC owes it?
ARP is a broadcast packet sent and all the computers except the destinated one rejects the packet
If any computer owes the IP replies : my MAC is xxx and my IP is abc
This is ARP
RARP : I know the AMC address whats the IP address
This is reverse address resolution protocol, where a MAC address is known and Ip address is needed.
8. How are email client and web mail different?
9. What is project 802?
this is for standardisation of ethernet (wired and wireless)

here are few more questions:


1. Difference between Hub, Router and Switch
2.How are collisons avioded in a switching domain
3.What is link aggregation
4.What is port mirroring
5.Explain RIP
6.How are routing loops avoided in RIP. explain both the methos
7.What is OSPF
8.Explain OSPF states
9.what are the types of LSAs?
10. What are the various tables used in OSPF?
11. What is a DR and what is BDR? How are they nominated?
12. What is a VLAN
13. If a switch has 3 VLANs how is the data flow then?
14.Can wireshark be applied on routers?
15 consider L1 <–> S1<–>R1 <–>R2
is it possible for a computer on L1 be able to snip packets between R1 and R2?
16 in case the structure is changed to R1 <–>H1<–>R2.
in this case is it possible for a computer connected to H1 be able to sniff packets betwen R1 and R2
17 what is the difference between RIPv1 and RIPv2
18what is autonomous system in OSPF
19asked me to subnet one of the IP address ( he gave me a host address)
20commands used to configure OSPF on cisco routers
21 how do you see the neighbour tables for OSPF on CISCO router
22 what does a hub do when it recieves a packet with unknown destination
23 what does a switch do when it recieves a packet of unknown destination