This document lists 100 interview questions for a CCNA certification covering topics like the OSI model, IP addressing, switching, routing protocols like OSPF and EIGRP, WAN technologies, network security concepts, and basic Cisco device configuration and troubleshooting. The questions assess knowledge of networking fundamentals including Ethernet, TCP/IP, VLANs, STP, routing, NAT, ACLs, firewalls, VPNs, and more.

1. CCNA Interview Questions for a fresher
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Explain about OSI Model, giving an example of communication between two hosts?
What are broadcast, multicast & unicast?
What is Ethernet? Explain about Ethernet frames?
Explain about IP Address,size,format?
What are the different classes of IP addresses and their range?
What is subnet mask, subnet mask of class a,b,c?
What is the difference between private and public ips?
Range of private ip for Class A, Class B,Class C?
What is TCP/IP?
What is the difference between TCP and UDP?
What are the functions of transport layer?
How can we subnet an ip address so that we have only 2 valid hosts for every subnet?
What is port numbers of transport layer? What is their significance?
What is DHCP? What is its use? Explain DORA process?
What is the L4 protocol type and port number of these protocols:
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HTTP
DNS
DHCP
POP3
LDAP
SSL
TELNET
SSH
IMAP
FTP
TFTP
HTTPS
What is mac address, size of mac address?
What is ARP? Explain ARP process?
What is APIPA? What is their advantage?
What is ICMP?
Explain about ping and tracert utility?
What is the difference between a hub, switch & router?
What are the different functions of a switch?
How does a switch learn mac address to its cam table?
What do you mean by single broadcast domain and collision domain?
What is CSMA/CD?
How does a switch forward traffic? Explain?
What are the different port modes in a switch?

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What are vlans? Why we use vlans?
By default how many vlans will be present in a switch?
What is a trunk? Explain its significance?
What are the two encapsulations in a trunk?
If both ports of a link connecting 2 switches are in dynamic auto mode, does the link become trunk?
What is Native vlan,Management vlan and user vlans?
What is vtp?
What are the three modes of vtp, explain each?
What is vtp configuration revision number?
What is intervlan routing, Give two methods for intervlan routing?
What is STP?
Explain operation of STP?
How a root is elected in STP?
What is BPDU? What does it contain? Size of BPDU?
What is BPDU hello interval? Max age and forward delay time?
If there is a tie is STP Cost how it is resolved in STP Operation?
How does a switch know a stp topology change?
What is PVST+? What is the advantage of using pvst+?
What are the port states of STP?
What is RSTP? What are its port states?
What is Portfast?
What is MLS, explain? Give some examples of L2 Switch and MLS
What is routing, what are the two types of routing?
Explain different types of dynamic routing protocols?
What is default routing? Where we can use default routes?
Explain about OSPF?
What is an ospf hello message? What does it contain?
What is AD and routing algorithm of ospf?
What can be the possible reason for ospf routers not becoming neighbors?
Multicast ip of Ospf?
Hello interval and dead interval of ospf?
What are different OSPF LSA Types? Explain in brief?
What is OSPF Metric?
What is ospf area? What is the purpose of using multiarea OSPF?
What is DR & BDR in OSPF? What type of OSPF network do they belong to?
What is OSPF router-id and how it is selected?
What are the advantages and disadvantages of using OSPF?
What is the difference between OSPFv2 & OSPFv3
Explain about EIGRP?
What does EIGRP hello message contain?
What is EIGRP AS Number?
Routing Algorithm and AD of EIGRP?

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What are the special features of EIGRP that makes it better than OSPF?
What is the multicast ip of EIGRP Hello messages?
What is EIGRP Metric?
What is Successor, feasible successor and feasible distance in EIGRP?
What is the difference between eigrp active and passive state?
Multicast ip address for OSPF and EIGRP?
What is NAT? Why do we use NAT?
What are the three types of NAT?
What is an Access Control list? What are the applications of ACLs?
Distinguish the two types of Access Control List?
How can we deny remote access to a router for configuration?
What is the range of standard and extended access list numbers?
How can we perform L3 Redundancy in a switched network?
What is FHRP?
Explain difference between HSRP and GLBP?
How can we make an HSRP gateway active?
What is HSRP and GLBP multicast ip address?
Explain working of HSRP? What is well known mac address of HSRP?
What is etherchannel?
What are the two etherchannnel protocols? explain their modes?
What is IPv6 address format andsize? Explain linklocal ipv6 address?
What is CDP? Which layer CDP works, What is its use?
Suppose you are not using a Cisco device, instead of CDP which protocol can be used?
Suppose a PC is not getting IP Address, how can you troubleshoot the issue?
What is VPN? Explain different types of VPN?
Explain Authentication, accounting and authorization functions of vpn?
Explain the different types of WAN Protocols used in a leased line WAN
What is NBMA Network and what is the L2 WAN protocol used in an NBMA Network?
What are DLCI's in Frame Relay?
What are the commands for the following operations:
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To view running-configuration of a Cisco device
To view interface status of a Cisco device
To view the IOS version and hardware platform
To add a static route
To enable routing in an L3 Switch
Create and assign vlans to ports
To clear all the configurations in a switch
To backup startup-config to tftp server
To view the routing table
To check logs of a cisco switch
To make a switch as root for vlan 1
Prepared by Rahul E [rahule@live.com]