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CCNA Interview Questions and Answers for 2024
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CCNA Interview Questions and Answers

Published On: April 1, 2022
CCNA (Cisco Certified Network Associate) is an inevitable IT certification for gaining jobs in top companies. The CCNA jobs involve the validated knowledge of installing, configuring, operating, and troubleshooting switched and routed networks within the enterprises. Obtaining the CCNA certification ensures the in-depth knowledge and understanding of networking and hardworking concepts that are essential to getting jobs. Here are the popular CCNA Interview Questions and Answers for you to prepare for the technical rounds of top companies.

CCNA Interview Questions and Answers for Freshers

1. Define Routing

Routing is a process of finding and establishing a path for data to pass from source to destination. It will be performed in many types of networks namely circuit-switched networks, computer networks, etc. Routing is done by a device known as routers that are layer devices.

2. What is the use of data links?

The purpose of the Data link layer is to verify messages whether are sent to the right device and another function of the data link layer is framing. The major purposes of the data link layer are framing and link access, reliable delivery, flow control, error detection, error correction, and half-duplex and full-duplex. It ensures that the particular physical protocol is assigned properly to the data.

3. Define Data Packets?

Data Packet is a unit that is made into a single package for transmission across a network. They are also defined as a network layer package and used by IP protocol as they consist of the IP information that is attached to each packet. Data packets have essentials messages like email messages, VoIP (Voice over IP) calls, website data, etc. Every data packet will have a unique numeric identification number to define the packet number and order.

4. What are the major functions of Routers?

The router is a device that forward data packets within a network from source to destination. They are designed to receive, analyze, and forward data packets between computer networks by examining a destination IP address of a data packet. It uses headers and a routing table to find the best way or route for passing the data packets. Popular companies that are developing routers are HP, Cisco, Juniper, Nortel, etc. The major functions of routers are,
  • Sending and receiving data over computer networks
  • Using to create a local network of devices
  • Helping to connect multiple devices to the internet
  • Allowing users to configure the port according to the needs of the network
  • Filtering unwanted interference and carrying out the process of data encapsulation and decapsulation
  • Using to segment network traffic
  • Preventing network bottlenecks by isolating portions of a network
  • Reducing excessive traffic.

5. What are the types of routes that are available in routers?

Types of routes in routers are static routing, dynamic routing, and default routing.
  • Static routing is a non-adaptive route and it is either directly configured on an active interface of the router or manually updated to the routing table by an admin.
  • Default routing is configured to send all packets towards a single router and it doesn’t consider whether it belongs to a specific network. It is used while the networks deal with a single exit point
  • Dynamic Routing is the adaptive route that makes automatic adjustments to the routes according to the current state of the route in the routing table and is also used in routing protocols to determine network destinations.

6. Define Switching and name two parts of Switching

Switching is the process in computer networks that allows us to connect internally through links for forming a larger network and it works at the DLL frame by using the hardware address or mac address of devices on LAN (Local Area Network) to segment a network. The two parts of Switching are Access Port and Trunk Port. Access Port connects network hosts to a single VLAN and carries the traffic of one VLAN. The traffic is sent and received in native format and it doesn’t require VLAN tagging. Access ports are used to connect switch ports with computers with a minimum of 10mbps speed. Trunk Port connects to another switch to interact with several other VLANs. It is a member of all VLANs in the VLAN database by default. The trunk port is used to establish multiple connections between the switch to switch and switch to routers.

7. List out the various IPX access list

There are two different IPX access lists below
  • Standard IPX access list used to filter the source or destination IP address
  • Extended IPX access list used to source and destination IP addresses, protocol, socket, and port when filtering a network.

8. What are the key advantages of Switches?

When a switch receives a signal, it creates a frame out of the bits that were from that signal. Using this process, it obtains access and reads the destination address and it forwards that frame to the appropriate port. This is efficient means of data transmission instead of broadcasting it on all ports.

9. When does the congestion occur in-network?

Network congestion will occur when there are too many users are trying to use the same bandwidth and this is true in big networks that will not resort to network segmentation.

10. Define the window in networking

A window in networking refers to the number of segments that are allowed to be sent from source to destination before an acknowledgment is sent back.

11. What is the main purpose of the transport layer?

The transport layer of the OSI model is responsible for providing transparent data transfer of data among end-users. It provides reliable data transfer services to the top layers and the main objective of the transport layer is to deliver the entire message from source to destination. The services of the transport layer are end-to-end delivery, reliable delivery, addressing, flow control, and multiplexing.

12. What is 100BaseFX?

100BaseFX is an ethernet media standard for ethernet across fiber optic cables instead of twisted-pair cables. It is a version of Fast Ethernet of uses fiber optic cables as the main transmission medium. 100 is referring to 100mbps data speed which means it carries data at 100mbps in LAN. The categories of Fast Ethernet are 100BaseX and 100BaseT4. The 100BaseX is further classified into two parts such as 100Base-TX and 100Base-FX.

13. List out the various memories used in Cisco routers

The various memories used in Cisco routers are

  • NVRAM (Non-volatile RAM) is used to store startup configuration files and it also retains its content even after a device is rebooted or powered down.
  • DRAM (Dynamic Random Access Memory) is used to store configuration files that are being executed and it loses its content once the device is restarted.
  • ROM (Read Only Memory) is used to store a bootstrap program that initialized a boot process and it also runs and maintains instructions for POST diagnostics.
  • Flash Memory is used to store Cisco iOS and it can also be used to store files such as configuration files.

14. What is HDLC?

HDLC stands for High-Level Data Link Control which is a group of communication protocols that usually provides reliable delivery of data frames across communication or network link. It is a proprietary protocol for CISCO and it is the default encapsulation operated within CISCO routers. It ensures the error-free transmission of data and provides both connection-based and connectionless services.

15. Define tracert and traceroute

Tracert is a Command Prompt used to show various details of the path that data packets will take from the source machine to the particular destination machine. It uses ICMP (Internet Control Message Protocol) echo requests and it can be used on a PC. This command is used in Windows NT-based operating systems. Traceroute is a command used to trace and record the path that data packets are taken from source to destination by using UDP (User Datagram Protocol) echo requests. Traceroute is used on a router or switch and it is used in UNIX operating system.

16. Explain DLCI

DLCI stands for Data Link Connection Identifier which is a frame relay 10-bit-wide link-local virtual circuit assigned normally by frame relay service to identify uniquely on the network. It identifies which of the logical circuit the data travels over.

17. What is the LAN switching method used in Cisco Catalyst 5000?

The store-and-forward switching method is used in Cisco Catalyst 5000 for storing the entire frame to its buffers and performs a CRC check before determining whether or not to forward that data frame.

18. What is the purpose of the LLC sublayer?

The LLC (Logical Link Control) sublayer provides optional services to an application developer. One option is to offer flow control to the network layer by implementing stop or start codes. The LLC also provides error correction.

19. Define BootP

BootP is a protocol used to boot diskless workstations that are connected to the network. It is a quick start for the boot program. Diskless workstations use BootP to find their own IP address and the IP address to the server PC.

20. What is the usage of Application Layer in Networking?

The Application Layer supports the communication components of an application to provide network services to application processes that span over the OSI reference model specifications. It synchronizes applications on the server and client.

21. What is the difference between User Mode and Privileged Mode?

User Mode is used to perform a regular task while using a Cisco router for viewing system information, check the status of the router, and connecting to remote devices. While the privileged mode contains all options that are available for User Mode. It can be used to make configurations on the router that includes making tests and debugging.

22. Explain the three different ways of data transmission in CCNA

Simplex: The communication is unidirectional in this mode as on a single-direction road. Using this, one of the two devices of a connection can communicate and the other can just get. In this simplex mode, the whole limit of the channel will be utilized to send information in one way. Half-duplex: In half-duplex, a device can transmit and receive simultaneously. When one device is sending the other will receive and vice versa. It is utilized when there is no requirement for communication in both ways and the whole limit of the channel will be utilized in every direction. Full-duplex: In full-duplex mode, both the transmitting device and the receiving device can communicate simultaneously which means both can be transmitting and receiving at the same time. Signals are going in one direction share the capacity of the connection with signals going in the other way. The sharing will happen in two ways: either the connection should contain two truly separate transmission ways. If one is for sending and the other for receiving or the capacity is split between signals going in two ways. The limit or capacity of the channel will be split between the two directions anyway.

23. Explain Frame Relay

Frame Relay is a packet-switching technology used to transfer data between geographically separated LANs across WANs. It simply offers connection-oriented communication by developing and maintaining virtual circuits. It is cost-efficient technology used to join two or more routers with a single interface and it works on the data link layer and physical layer of the OSI model.

24. What are the various types of cables used in routing?

There are three different types of cables used in routing such as straight cable, cross cable, and rollover cable.
  • Straight cables are used to connect various groups of devices. They are used in LAN to connect various devices such as computers to a network hub like a Router, Switch, and PC. Its primary goal is to connect a host to the client.
  • Cross Cables are used to connect the same group of devices and it is considered one of the most commonly used cable formats for network cables. It is used when two similar devices are connected. They are also known as cross-wired cables.
  • Rollover Cables are used to connect the console port of the computer. It is designed flat to help distinguish it from other types of cables. It allows programmers to connect to network devices and also manipulate the programming whenever required. They are also referred to as Yost Cable, Console Cable, or Cisco Cable.

25. How can you depict an IP address?

To depict an IP address there are three possible ways as follows
  • Using dotted-decimal like
  • Using Binary like 10000010.00111011.01110010.01110010
  • Using Hexadecimal like 82 1E 10 A1

CCNA Interview Questions and Answers for Experienced

26. Explain EIGRP with some metrics

EIGRP is the acronym for Enhanced Interior Gateway Routing Protocol which refers to Cisco’s IGP (Interior Gateway Protocol) used on a computer network. It is used to automate routing decisions and configurations. It is suitable for various topologies and media and it is used widely on a router to share routes within the same autonomous system. It includes metrics such as Bandwidth, Load, Delay, Reliability, MTU, and Maximum Transmission Unit.

27. Write a short note about CDP and its functions

CDP stands for Cisco Discovery Protocol is a Layer 2, network-independent, and media-independent protocol that runs on all the Cisco devices helps us to discover Cisco devices on the network. It works based on the MAC address and it also initiates the management of Cisco devices by finding the devices, identifying how to configure devices, and enabling them to understand each other using various network-layer protocols. Some of its functions are as follows.
  • Collecting information of directly connected neighboring devices
  • Finding adjacent Cisco devices, port numbers, IP addresses, switch models, router models, iOS details, interface details, and device ID-hostname.
  • Simplifying the process of keeping an up-to-date inventory of Cisco network devices
  • Sharing information of other directly connected devices like IP addresses and OS versions.

28. Define VLAN with its primary objective.

VLAN is the abbreviation of Virtual Local Area Network is a logical group of workstations, network devices, and services that communicate with each other on a separate physical LAN. It enhances the network performance or applies additional security features. The main objective of VLAN is to allow various networks to perform virtually as if they were a LAN that shares a single broadcast domain.

29. List some of the benefits of VLAN

The benefits of VLAN are as follows
  • The latency and traffic load on the network will be removed easily
  • Network resources will be saved and network efficiency will be increased
  • Its cost and the incidence of collisions will be reduced
  • Network security and performance will be improved
  • Network flexibility will be ensured and easier management will be provided
  • Relocating a network or a network device is easier with VLAN
  • Number of broadcast domains can be increased while decreasing the size of broadcast domains.
  • Broadcast domains in switched networks will be established easily with VLAN

30. Explain about Broadcast domain and Collision domain.

Broadcast Domain is a logical set of reachable computer systems that are without a router connection. In the broadcast domain, traffic flows all over the network and when a device sends a broadcast message, then all the other devices present in its broadcast domain have to prepare for it. A collision domain is a part of a network where packet collisions can take place when being sent on a shared medium or through repeaters. In the collision domain, when a device sends a message to a network, then all the devices present in it prepare for receiving data even it was destined for them.

31. Differentiate static and dynamic IP Addressing

Static IP Addressing is simply an IP address that doesn’t change. Unless the device is decommissioned or the network architecture is changed, the IP address will remain the same for the device. Dynamic IP address, on the other hand, the IP address will change over time and it is mostly used as IPv4 can’t provide static IP addresses to go around.
Static IP Address Dynamic IP Address
Provided by ISP (Internet Service Provider) Provided by DHCP (Dynamic Host Configuration Protocol)
IP Address doesn’t change when it is assigned as static by an admin. The IP Address will change over time when it is assigned as a dynamic.
Less secure and more difficult to designate More secure and easy to designate
Suitable for a business Suitable for home network
Requires costlier deployment and is more difficult to manage Cheaper deployment and easy to manage
Appropriate for dedicated services like VPN, FTP, and mail servers Appropriate for a large network that needs internet access to all devices
Used widely for computational data that are more confidential Widely used where data is more confidential and needs a high level of security.

32. Explain the two types of networks in CCNA

The two types of networks in CCNA are Server-based networks and Peer-to-peer networks. Server-based network: This network is also known as a client-server network. The clients will be served by a node called a server. The centralized server is used to store the data as its management is centralized with a server. Peer-to-peer network: This network is also known as a computer-to-computer network or P2P. Nodes or computers are addressed as Peers that are connected to one another. Each node in this network is connected to another node.

33. List out the passwords that can be used in Cisco Routers

The passwords that can be used in Cisco Routers include the following
  • Enabled: A global command that disables privileged execution mode and the password can’t be encrypted. To change the password, we can use “enable password password”.
  • Enable Secret: To enable a password in a particular place, the secret password is used. To change it, we can use “enable secret password”
  • AUX (Auxiliary): Auxiliary passwords are set for auxiliary ports and through a modem, a router can be accessed through the auxiliary port.
  • Console: Console port passwords will be set using the console password.
  • VTY (Virtual Terminal): We need the virtual terminal password for telnet sessions into the router. These passwords can be changed at any time and we can set them up when we configure the router from the console.

34. Differentiate Public IP and Private IP

Public IP is used in public networks whereas private IP is used within a private network or LAN to connect securely with other devices within the same network. Public IP is assigned by a service provider or IANA while private IP is assigned by an administrator of LAN. Public IP is used to communicate outside the network but private IP is used to communicate within the same network. Public IP can be known by searching with the “what is my IP” keyword in google where Private IP is known by typing “ipconfig” on the command prompt. The scope of Public IP is global but the scope of private IP is local to the present network. Public IP comes up with a cost and is controlled by ISP and the Private IP is free of cost and used to load the network operating system. It is routable for communication among different users is possible with Public IP. But the routable and communication with other users are not possible in Private IP. Public IP will be any number range for reserving public IP address. But there is a range to reserve private IP addresses. The example for public IP is 240:201:006:14:98:16. The ranges for private IP addresses are to for Class A. to for Class B. for Class C. An example for Private IP is:

35. Differentiate TCP and UDP

TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are two different protocols to send files across computer networks. Following are the differences between TCP and UDP
TCP is a connection-oriented protocol. Once the connection is lost during the file transferring process, the server would request the lost part. While transferring a message, there should be no corruption in TCP. UDP is a connectionless protocol and once the user sends data, there is no guarantee whether your transferred message will reach there without any data loss.
The message will deliver in the order as it is sent. The user’s message may not be in the same order
Data will be read as a stream in TCP. When one packet ends and another begins. Packets are transferred individually and assured to be whole when they reach.
Examples of TCP are World Wide Web, e-mail, and file transfer protocol. Examples of UDP are TFTP (Trivial File Transfer Protocol) and VOIP (Voice Over Internet Protocol).

36. What is the factor to be considered in determining the OSPF router ID while configuring a router that utilizes both physical and logical interfaces?

The highest IP address of any physical interface to be considered in determining the OSPF router ID when configuring a router for physical and logical interface utilization.

37. Define Route Poisoning

Route Poisoning is the process of inserting a table entry of 16 to a route to make it unreachable. This technique is to prevent issues that happened to inconsistent updates on a route.

38. What is the main function of the application layer in networking?

The topmost of the OSI model is the application layer used by end-user software for web browsers and email clients. It is the layer that users interact through and it contains some protocols that are focused on process-to-process communication over an IP network. It includes the following
  • Manage data exchange in a client-server networking or a peer-to-peer model
  • Provide end-user services and a firm communication interface
  • Enables users to access the network
  • Provide the base for storage facilities and email forwarding
  • Enable access to global information for various services.

39. What is PoE?

PoE (Power of Ethernet) refers to a technology that enables electric power to be carried across the Ethernet cable that passes data. It transfers the electric power supply to the network via the cable instead of power cards and minimizes the number of wires needed to install the network.

40. What is OSPF?

OSPF stands for Open Shortest Path First is a widely used link-state routing protocol for IP networks used to connect to a large number of networks without any limitation on the hops. It decides the best route for delivering the data packets within an IP network. It has been applied by a wide range of network clients such as Cisco. It works according to the Dijkstra Algorithm.
  • At first, a shortest-path tree is constructed
  • Then, the routing table will be populated with the resulting best paths.

41. Define RIP

RIP is the acronym for Routing Information Protocol which is the distance vector-based routing protocol. It is used to calculate the metric based on hop count. RIP is an industry-standard dynamic protocol used for smaller-sized enterprises. It is denoted by ‘R’ in the routing table and supports 15 routers at the maximum. Users can’t create a separate administrative limit in the network in the RIP routing protocol.

42. What is IGRP?

IGRP is an abbreviation of Interior Gateway Routing Protocol that is a distance vector-based interior gateway routing protocol. It is used to calculate the metric based on bandwidth, delay, and load. It is a Cisco standard dynamic protocol and is used for medium to large-sized companies. It is defined by ‘I’ in the routing tables and supports 255 routers at the maximum. Users can create a separate administrative limit in the network using the autonomous system in the IGRP routing protocol.

43. Define network congestion and explain when it happens

Network congestion occurs when a network node is overloaded with data or traffic and creates a common issue for admins. It occurs when the network is carrying or transferring an exceeding amount of data than the routers and switches can accommodate. It results to become too full when many users try using the same bandwidth in the internet route. The condition will be true in big networks that don’t resort to network segmentation.

44. What is a hold-down and how does it work?

Hold-downs are used to prevent regular update messages from reinstating a downed link by deleting that link from update messages. It resets the hold-down timer using triggered updates.

45. Differentiate Switch and Hub

Factors Switch Hub
Definition A switch is a control unit that turns the electricity flow on or off in a circuit Hub is a networking device that connects multiple devices to a single network.
Related Layer Used in the data link layer Used in the physical layer
Type of transmission Broadcast at first, then is unicast Unicast, multicast, or broadcast
Ports 24/48 ports 4/12 ports
Mode of transmission Half and full-duplex Half-duplex
Chances of collision No collision occurs in a full-duplex switch mode Collisions will occur commonly
Address for data transmission MAC address for data transmission MAC address for data transmission
Form of data transmission Frame Electric signal

46. List some of the examples of routers

Brouter: It stands for Bridge Router that serves both as a bridge and a router Core Router: It is a router in the computer network that routes the data within a network but not between the networks. Edge Router: This is a router that resides at the boundary of a network Virtual Router: It is a software-based router that performs the packet routing functionality by a software application. The redundancy protocol of a virtual router implements the virtual router to improve the reliability of the network. Wireless Router: It is a router that connects the local networks with another local network.

47. Differentiate CSMA/CD and CSMA/CA

CSMA/CD is the acronym for Carrier Sense Multiple Access with Collision Detection which is a media access control method that is used in local area networking with the use of Ethernet technology to overcome the occurred collision. If CSMA/CD finds the collision, it stops continuing the data transmission. Here, wireless installation is being used to detect collision and it affects the occurrence of a collision. CSMA/CD is using 802.3 Ethernet Network Technology. CSMA/CA is an abbreviation of Carrier Sense Multiple Access with Collision Avoidance that is used in wireless networking to avoid collision. It doesn’t deal with the recovery of the collision and it is using wireless installation to avoid the collision. It is not a wired network and it is using 802.11 Ethernet Network Technology. CSMA/CA takes action even before the collision occurs in the network.

48. List the protocol data units in CCNA

PDU (Protocol Data Units) are the minimum possible units of the OSI model for data transporting and it is used in various layers. In the transport layer they are segments, In the network layer, they are packets and datagrams, in the data-link layer, they are frames, and in the physical layer, they are bits.

49. Differentiate ARP and RARP

ARP is the acronym for Address Resolution Protocol used to map an IP address to a physical machine address (MAC Address). RARP stands for Reverse Address Resolution Protocol used to map MAC address to IP address. The major differences are ARP contains the logical address and retrieves the physical address of the receiver while RARP contains the physical address to retrieve the logical address of a computer from the server. ARP is used to map 32-bit logical addresses to 48-bit physical addresses while RARP is used to map 48-bit physical addresses to 32-bit logical addresses.

50. Explain the various topologies of CCNA

Topology is an arrangement of different elements such as links or nodes of a computer network with a specific order and the following are the types of topologies used in CCNA Bus Topology: It is a network topology in which all the nodes are connected to a single cable called a central cable or bus. It serves as a shared communication medium. If any device wants to send the data to other devices, it will send the data over the bus that turns to send the data to all the attached devices of a network. It is used for a small number of connected devices in a network and if the bus is damaged then the whole network will fail in data transmission. Star Topology: It is a network topology that which all the nodes are connected to a single device known as a central device and it requires more cable compared to other topologies. It is more robust as a failure in one cable leads to disconnecting a specific computer connected with a cable. If the central device is damaged then the whole network will fail. It is very easy to install, manage, and troubleshoot and it is commonly used in office and home networks. Ring Topology: It is a network topology in which nodes are connected exactly to two or more nodes to form a single continuous path for the data transmission. It doesn’t require any central node or server to control the connected devices. If any single node is damaged, then the whole network will fail. It is used very rarely as it is very expensive and it is very difficult to install and manage. Examples of Ring topology are the SDH network and SONET network. Mesh Topology: It is a network topology in which all the nodes are connected individually to other nodes and they don’t require a central switch or hub to control the connectivity among them. It is categorized into two parts such as fully connected mesh topology where all the nodes are connected to each other and partially connected mesh topology where all the nodes are not connected to each other. It is robust as a failure in one cable will be disconnected the particular computer connected to this cable. Mesh topologies are used rarely as the installation and configuration are difficult when connectivity is high. Cabling cost is also very high as it needs bulk wiring. Tree Topology: It is a combination of star and bus topologies. It is also referred to as the expanded star topology. Here, all the star networks are connected to a single bus. This topology is using Ethernet protocol. The whole network is segregated into segments called star networks that can be easily maintained. If one segment is damaged, there will be no effect on other segments. This topology depends on the “main bus” and if it breaks then the whole network gets damaged. Hybrid Topology: It is the combination of various topologies to form a resulting topology. If the star topology is connected with another star topology, then it remains star topology but the star topology is connected with any other topology then it will become a Hybrid topology. It offers flexibility as it can be applied on various network platforms. The weakness of topology is avoided or ignored; the strength will be taken into the consideration.
Conclusion CCNA is the foundational certification that requires entering any entry-level jobs in hardware and networking jobs in companies. CCNA certification brings promising jobs and career growth for learners around the world. Our “CCNA Interview Questions and Answers help you definitely to get into the networking jobs and improve your understanding and skill level that the company requires. Join our CCNA Training Institute in Chennai to learn the best CCNA Course with complete hands-on exposure.
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