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Interview Questions For CCNA

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By: Vijay Maripi

December 6, 2021

Overview of CCNA

A Cisco Certified Network Associate (CCNA) is a certification exam offered by Cisco. Candidates with CCNA certification will have access to new jobs in a competitive networking area. The abilities and expertise will propel the career to the pinnacle of networking in the IT profession. CCNA is a constantly changing sector that requires students and professionals to update their abilities with new features and knowledge to be qualified for the jobs linked with it. With thousands of jobs available for CCNA developers, specialists must be familiar with all CCNA technologies. CCNA certification can help you get higher-level and entry-level networking jobs.

Concepts to understand before the interview

OSI Model and TCP/IP Model

The Open Systems Interconnection model (OSI) standardizes communication within Network Systems by breaking it down into different layers. This model drives all Cisco hardware, and one must be familiar with all seven model layers. the seven layers are:

  • Application Layer
  • Presentation Layer
  • Session Layer
  • Transport Layer
  • Network Layer
  • Data Link Layer
  • Physical Layer

To completely understand the concepts of the OSI model, it is essential to understand what each layer functions and how each layer interacts with one another.

The Transmission Control Protocol (TCP) and the Internet Protocol (IP) are two independent network protocols; they are sometimes used interchangeably to define the standard data transmission architecture used by the local area networks and the internet.


Subnetting is a network technique for dividing huge networks into smaller parts. Each subnet has an IP address, and the components of each subnet often have shared values.


IPv6 is an Internet Protocol. IPv6 was created to remedy various shortcomings of IPv4, most notably the issue of IPv4 address limitation. In contrast to IPv4, which has only roughly 4.3 billion (2 raised to power 32) addresses available, IPv6 has 3.4 × 10 raised to power 38 addresses.

Network Address Translation

The technique of altering IP address information in IPv4 headers while in transit across a network is known as Network Address Translation (NAT). A one-to-one translation, also known as basic NAT, is the most basic type of NAT. This is used to join two IP networks that have conflicting addressing schemes.

Other Concepts to understand:

  • Understand how TCP/IP varies from OSI model
  • How subnetting works in the real world
  • Know about static routing
  • Understand how LAN switching works
  • Know about dynamic routing protocols
  • Understand how PPP (point-to-point protocol) works
  • Know about spanning tree protocol

To learn more about Cisco Certified Network Associate or CCNA, refer to:

Job oriented interview questions

  1. What is meant by Routing?

The technique of determining the best path for transporting data from source to destination is known as routing. Routing is accomplished through the use of a device known as a router. A router is a device at the network layer.

  1. What is meant by Networking?

Networking is the process of connecting to or operating a network. It is the process of developing and deploying wired or wireless networks to exchange data, files, and other forms of electronic communication.

  1. What is the use of the Data Link Layer?

The function of the Data Link layer is to ensure that messages are delivered to the correct device. This layer also functions as a framing.

  1. What is meant by subnet?

A subnet, sometimes known as a subnetwork, is a split section of a larger network. Subnets are a logical division of an IP network into many smaller network pieces. The Internet Protocol (IP) is a technique of transmitting data from one computer to another via the internet. As a unique identification, each host or computer on the internet has at least one IP address.

  1. What is the use of a switch?

A switch connects to other devices through Ethernet connections in a wired network. The switch enables each linked device to communicate with the others. Wireless-only networks do not utilize switches because wireless routers and adapters connect directly.

  1. What is the OSI model?

The OSI (Open Systems Interconnection) model defines seven layers through which computer systems communicate over a network.

  1. When will Network Congestion occur?

Network congestion occurs when the network is carrying/exchanging more data than it can comfortably handle. When many users use the same bandwidth, then the network becomes congested. This is particularly true in large networks that do not use network segmentation.

  1. Can a bridge divide a network into smaller sections?

A bridge cannot divide a network into smaller sections. A bridge is a network device that links two or more LANs (local area networks) to build a larger LAN. Network bridging refers to the process of aggregating networks. A bridge joins the various components, appearing to be part of a single network.

  1. What is HDLC?

HDLC (High-level Data Link Control) is a set of protocols or rules for data transmission between network nodes.

  1. What is MTU?

MTU is an acronym for maximum transmission unit, and it represents the largest packet size that can be delivered on a data line without fragmentation.

  1. What are Full-duplex and Half-duplex?

Full-duplex means that information or communication is transmitted in both ways. Half-duplex means that information or communication is only transmitted in one way.

  1. What is PING utility?

Ping (Packet Internet Gopher) is a program that checks connections to one or more remote hosts. The ping command checks whether an IP system on a network is operational by sending ICMP echo requests and echo reply packets. Ping can be used to troubleshoot IP network or router issues.

  1. Why is the H.323 protocol used?

H.323 is a multi-service (multimedia) protocol commonly used in a Voice Over IP setting.

  1. What is BootP?

BootP is a protocol for booting network-connected diskless workstations. It is an acronym for Boot Program. Diskless workstations also use BootP to determine their IP address and the IP address of the server PC.

  1. What are the private IP ranges?

Class A IP range: from to Class Bb IP range: from to Class Cc IP range: from to

  1. What is the use of VLAN?

VLAN stands for Virtual LAN network, and it is used to create a separate domain within a single switch.

  1. How is straight cable different from cross cable?

Straight cables are used to connect a different group of devices, while Cross cables are used to connect the same group of devices.

  1. What is 100BaseFX?

This is Ethernet with fiber optic cable as the primary communication medium. The 100 represents the data speed, which is 100Mbps.

  1. What is meant by route poisoning?

Route poisoning is a method of stopping a network from transmitting packets through a route that has become invalid.

  1. Given the address and the subnet mask of How many hosts are available?

172.16.2 120 is a standard Class B address with a subnet mask that allows 254 hosts.

To practice more questions on networking, refer to:

The above-mentioned interview questions may vary based on organization and job roles.


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