Basic CCNA Networking Interview Questions & Answers

Looking for basic CCNA networking interview questions and answers for the preparation of CCNA interview, here is the best collection of some most frequently asked CCNA interview questions with answers. This collection of basic CCNA interview questions and answers helps you in preparing for CCNA job interview confidently.

This tutorial is the first part of our article “CCNA Job Interview Questions with Answers”. This part provides CCNA interview questions and answers from following sections; Network services, Internetworking, Network types, network topology, communication message types, collision domain and broadcast domain.

Basic CCNA Networking Interview questions and Answers

In router, which service is used to translate the source IP address of a packet into the IP address of a public interface?

In router, NAT (Network Address Translation) service is used to translate the IP addresses.

You are able to access a server by its IP address, but not by its name. Which service is responsible for this?

For this, DNS (Domain Name System) service is responsible. DNS service maps IP address with hostname. If you are able to access any object by its IP address, not by its name, it’s an indication that either DNS service is not configured or is not working properly.

Due to some security reasons a company wants to hide its actual server IP address from external world. Which service should it configure in router to achieve this goal?

NAT (Network address Translation) service allows us to translate an IP address. Company can configure this service to hide its internal IP structure from the external world. It can configure NAT service in a router which connects it with external world.

NAT example

Which service ISP uses to provide Internet access to the multiple computers from single IP address?

PAT (Port Address Translation) service allows computers to use a unique combination of IP address and port address to connect with Internet. To make it unique, different port address is used in each combination.

You are asked to connect two branch offices which are using same IP addresses. Due to some technical reasons you are not allowed to make any change in existing IP structure of both offices. Which service will you use to connect them?

To connect the two different networks which are using same IP addresses, NAT service is used. NAT service allows us to map different IP addresses with existing IP addresses. Later these different IP addresses can be used to connect with other network.

You want to assign IP addresses automatically to the devices in network. Which service will you use for this purpose?

To assign IP address automatically DHCP service is used. Based on availability of devices and requirement of network, this service can be configured in Server system, in Modem and in Router.

To obtain an IP address from DHCP server, which message a client system uses when it boots up?

A client system broadcasts several DHCP discovery messages in network with destination address of FF-FF-FF-FF-FF-FF at startup. If any DHCP server exists in network and receives the message, it will respond to the message for further process.

Which device is used to regenerate the signals so that they can travel a longer distance in network?

To regenerate the signals, repeater is used. Other devices such as switches and routers also enhance the signal quality. The difference between them and repeater is that they do this job as an add-on feature while repeaters only do this job. Since repeaters are built only for this particular task, they are blazingly fast and effective in comparison with other devices.

Which device filters and forwards data frame based on layer 2 MAC address?

Switch

Which device filters and forwards data packet based on layer 3 IP address?

Router

What is the difference between Half-duplex mode and Full-duplex mode?

Half-duplex mode and Full-duplex mode both terms define how a device transmits data in network. In Half-duplex mode, a device can only send or receive data at a time. It can’t perform both actions same time. While in Full-duplex mode, a device can send and receive data at the same time simultaneously.

What are the differences between broadcast, multicast and unicast messages?

Unicast message is sent to an individual system in network.

Multicast message is sent to multiple systems in network.

Broadcast message is sent to all systems in network.

broadcast types

Which destination MAC address is used in Broadcast message?

A broadcast message uses a destination MAC address of FF-FF-FF-FF-FF-FF.

What is the Broadcast domain?

Broadcast domain is a group of systems which can receive same broadcast message.

What is the Collision domain?

Collision domain is a group of systems which shares physical media access. If any collision occurs in media, all system from group will be affected.

How many broadcast domain and collision domain are created by hub, switch and router respectively?

Device Collision Domain Broadcast Domain
Hub Single collision domain Single broadcast domain
Switch Per port collision domain Single broadcast domain
Router Per port collision domain Per port collision domain

What is the VLAN?

VLAN is a layer2 approach to reduce the broadcast messages from network. By default a layer2 device such as switch doesn’t interrupt the broadcast message. It floods a broadcast message from all of its ports which creates a single broadcast domain. VLAN allows us to break this single broadcast domain in multiple smaller broadcast domains. Basically VLAN creates a logical boundary at layer2. Once VLANs are created and configured, devices from different VLANs are not allowed to communicate with each other. Just like different IP network, different VLANs need a layer3 device to communicate with each other.

A simple network without VLAN

network without vlan

Same network with VLAN

netwok with vlan

How many broadcast domains and collision domains are there in the network illustrate below?

number of broadcast and collision domain example

There are 3 broadcast domains and 6 collision domains in this network.

broadcast domian collision domian

What is the difference between fully meshed network and partially meshed network?

Meshing describes how the devices are connected with each other in a network. There are two types of meshing; fully and partially. In fully meshed network, each device is directly connected with every device in network while in partially meshed network each device is not connected with every device in network.

fully meshed partilly meshed network

How many links we need to make a network fully meshed which has 10 devices?

To calculate the required number of links in making a network fully meshed, use following formula: -

N x (N-1)/2

In this formula N is the number of devices.

10 x (10-1)/2 = 45

So, to make a 10 devices network fully meshed, we need 45 links.

What is the topology?

Topology is a method of connecting and arranging networking devices such as computers, laptops, switch, hub, router, etc. A network topology defines the way in which devices are connected with each other physically and logically.

What is the difference between physical topology and logical topology?

A physical topology defines how the devices are connected physically while a logical topology defines how the data is transported between devices.

How computer networks are categorized?

Computer networks are categorized based on their geographical location and characteristic.

Describe some popular computer network types based on their geographical location

LAN (Local Area Network): - A network which spans over a very small geographical area such as home, building, office, etc.

PAN (Pearson Area Network): - Same as LAN, but limited to a specific person or a location such as home network.

MAN (Metropolitan area networks): - A network which connects two or more LAN networks within same city.

CAN (Campus Area Network): - Same as MAN, but limited to a university or an academy.

WAN (Wide Area Network): - A network which spans over a large geographical area such as state, region, country etc.

GAN (Global Area Networks): - A network which connects two or more WANs and covers unlimited geographical area.

Describe some widely used computer networks based on their characteristic.

Internet: - The largest group of computer network available on the earth.

internet: - A network which is connected with an external network through a gateway such as BGP.

Intranet: - A network which is controlled and administered by a single entity such as company or organization.

Extranet: - An extended Intranet where external users are allowed to access a small portion of network is considered as extranet.

VPN (Virtual Private Network): - A private network which uses public network such as Internet for data transportation.

Client/Server Network: - A network where server system provides and client system accesses the shared resources.

Workgroup network: - A network where any system can provide and access shared resource.

Which topology uses a single cable to connect all devices?

Bus

Which topology uses a centralized device to connect all devices?

Star

What is computer networking?

Networking is a process of connecting two or more devices for data and resources sharing.

What is inter-networking?

Internetworking is a process of connecting two or more computer networks which use different technology.

That’s all for this part. In this part we discussed basic CCNA interview questions with and answers. In next part will discuss CCNA Interview questions and answers from OSI layer model.

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