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CISCO CCNA Interview Questions and Answers

What is CCNA?

CCNA stands for Cisco Certified Network Associate that is a certification offered by CISCO. Certified professionals can troubleshoot network problems, install and configure networks. They can identify security threats of the network, apply countermeasures and setup WAN links.

What are the different types of network in CCNA?

The different types of network are as follows:

  • LAN A Local Area Network covers a small area such as a campus, building or an office. It has high data rates.
  • WAN A Wide Area Network covers large distances like multiple cities or an entire country. Fibre optic cable may be used for these.
  • PAN A Personal Area network covers a very small area such as a room. WiFi and Bluetooth are examples of PAN.
  • VPN A Virtual Private Network allows users to log in a private network securely and access the private files remotely.
  • MAN Metropolitan Area Network is used to connect the network nodes across the same metropolitan area

What is a loopback address?

A loopback address is a special IP address 127.0.0.1. This is used by IT professionals for testing network applications and verifying the communication of a local network. The network is not connected to any network and has no hardware attached to it.

Data packets are transferred over this address and re-routed to the initial node without any modification.

What are the types of IP Address? 

There are two types of IP:

  • Dynamic IP
  • Static IP

What are CCNA Routing and Switching?

CCNA routing and switching is a certification that covers the basics of routing, switching, subnetting and IP addressing. In general, routing is the process of transferring data from a particular source to a destination. It is done through a router.

The channelling of input data between different networks is called switching. The switch helps to send data from many in input ports to destination ports.

Explain various types of routing in CCNA?

The various types of routing in CCNA are as follows:

  • Static routing Here, the routes are added manually to the routing table by the network administrator.
  • Default routing Here, the router is configured for sending data packets to a single hop device or router.
  • Dynamic routing The routes are adjusted automatically based on the state of the route. A new route may be added for each packet corresponding to the changes in the routing table.

What is the difference between OSI and TCP/IP model?

The OSI (Open System Interconnection) model is a model used for reference that is used to develop networks. Following a vertical approach, the transport layer here guarantees that data packets are delivered properly.

The TCP/IP (Transmission Control Protocol / Internet Protocol) is the model implemented based on the OSI model. Here, the transport layer does not guarantee the transmission of data packets. The model follows a horizontal approach.

The basic difference between the two models is that the TCP/IP model is a client-server model that is used for transferring data over a network. Whereas the OSI model is a conceptual model.  

What are the layers of the OSI model?

The different layers of the OSI model are as follows:

  • Layer1 - Physical
  • Layer2 - Data Link
  • Layer3 - Network
  • Layer4 - Transport
  • Layer5 - Session
  • Layer6 - Presentation
  • Layer7 - Application

Explain public and private IP address?

A public IP address is used for a public domain and is assigned to a system to access the internet directly. Through these addresses, web and email servers can be accessed over the internet.

A private IP address is provided by a device such as routers using NAT (Network Address Translation). This is a secure address and allows companies to develop their private networks. Systems within an organisation are allocated private IP addresses.

What is NAT?

NAT stands for Network Address Translation is a process through which a networking device assigns an address to a computing device within a private network. It is commonly used for limiting the amount of IP address an organisation uses.

It also translates the local IP addresses to global addresses.

What are the different types of NAT?

The different types of NAT are as follows:

  • Static NAT – Here, a private IP address is converted into a public address. For example, Web hosting.
  • Dynamic NAT Several private IP addresses are mapped to a group of public addresses.
  • PAT (Port Address Translation) Here, many private IP addresses can be translated into a single public address. Port numbers are used to determine which traffic belongs to a particular IP address.

What is NAT boost?

NAT boost is a technology that is used for enhancing the forwarding speed of data. It is an engine that is present within the CPU. It is able to reduce the network traffic from the CPU so that is can use its processing power more efficiently for other applications.

What is half-duplex and full-duplex?

Half-duplex and full-duplex are transmission modes in networking.

In half-duplex mode, each device or station can send or receive data. But this cannot be done simultaneously. If one device is transferring data, the other can only receive it. For example, Walkie-talkie communication

In full-duplex, both the devices can send and receive data at the same time. The channel capacity has to be distributed between the two stations. For example, telephone communication.

Explain BOOTP?

BOOTP stands for Bootstrap Protocol that is used to get an IP address by a client from a specific server. It establishes a network connection during the booting process of a system. Using this the client can also request the address of a name server and the gateway address.

It lays down the foundation for the DHCP (Dynamic Host Configuration Protocol).

What is a MAC address?

The MAC (Media Access Control) address is a unique number that identifies a user’s computer. This number is assigned to every Ethernet or network card by the manufacturer. It is also referred to as the physical address or the hardware address of the device. It is a number used for identifying the devices in a network. The address is permanent and cannot be changed. 

This is usually a 48-bit number that is a hexadecimal notation consisting of 12 digits. There are unicast, multicast and broadcast MAC addresses.

How many bits are in a MAC address?

A MAC address consists of 48 bits. It is a hexadecimal number having 12 digits. The initial 6 digits are used to identify the manufacturer. The 6 digits on the right represent the Network Interface Controller.

What is UTP?

UTP stands for Unshielded twisted pair that are used for making telephone wires and LAN cables. Here the conductors forming a single circuit are twisted. This cancels out the electromagnetic interference from outer sources. It is called unshielded as it has no covering or shield.

What is a major benefit of STP over UTP?

STP wires have the ability to send data at a faster rate than UTP. This is because it is shielded that blocks more electromagnetic interference than UTP, thus increasing the data transfer rate. The data sent through STP is more secure than UTP. Its internal and external components allow data to be sent without much delays and errors.

Explain 100BaseFX?

The 100BaseFX is a standard that is followed for setting up Fast Ethernet. Based on 802.3u, this standard provides a speed of 100Mbps. This is also capable of extending the distance of networks up to 1.2 miles using copper wires.

Explain the difference between IGRP and RIP.

IGRP stands for Interior Gateway Routing protocol that is used for creating an administrative boundary in any network. It used in small and medium corporations. A maximum of 255 routers can be supported in a network by IGRP.

RIP stands for Routing Information Protocol. It is a routing protocol that determines the fastest path between the source network and destination network. To do this, it uses the hop count. This is a measure of the number of routers between source and destination. In RIP, a separate administrative boundary cannot be created in any network. Small companies use it mostly. It can support 15 routers in a network.