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Introduction
CCNA (Cisco Certified Network Associate) is one of the most sought-after certifications in the networking industry, validating your knowledge of networking fundamentals, IP services, security, and automation. Whether you're starting your career in networking or looking to upgrade your skills, preparing for CCNA interview questions is crucial to land a job in network administration and support roles. This blog covers the Top CCNA Interview Questions and Answers for 2025.
CCNA Interview Questions for Beginners
1. Define networking.
Networking can be defined as computing devices that are connected together and can easily share resources and exchange information between them.
2. How do network devices communicate with each other?
The network devices communicate with each other by using a set of system rules. These system rules are called communication protocols.
3. Define protocols.
Protocols are defined as rules basis on which the transmission of data and resources takes place between interconnected computer devices.
4. What is a switch in networking?
A switch can be defined as a hardware device that allows connecting various devices within a network.
5. Define data packet.
A data packet can be defined as the basic unit of information. The unit of information can be transferred throughout the network.
6. What is the use of routers in networking?
Routers in networking allow transferring data packets to their right place. They allow connecting more than one network together. The flow of information between network devices is managed by routers.
7. What is a hub in networking?
A hub can be defined as a device that allows connecting various other devices together in a network.
8. Define the OSI model.
The OSI model stands for the Open Systems Interconnection Model. It can be defined as a model that allows systems to communicate with each other with the help of standard protocols. The OSI model is made by ISO(International Organization for Standardization).
9. How many layers are there in the OSI model?
There are seven layers in the OSI model. These are as follows.
Physical Layer
Data Link Layer
Network Layer
Transport Layer
Session Layer
Presentation Layer
Application Layer
10. How many ports are there in switches? Name them.
There are two ports in switches. These are as follows.
Access Port: It only carries traffic for a single VLAN.
Trunk Port: It carries traffic for multiple VLANs.
11. How do routers work in a network?
Routers work in such a way that they focus on looking for information using IP addresses. Then routers allow computing devices to request files or information from the server by accessing the internet. Then, routers make sure that the requested file or information must be received at the device that requested it.
12. What are the functions of routing?
There are many functions of routing in networking. A few of them are as follows.
Routing allows computer networks in sending and receiving information.
Routing helps in connecting more than one device to connect to the internet.
With the help of routing, we can easily configure network ports.
13. How can network connectivity issues troubleshooting?
There are many ways of troubleshooting issues in network connectivity. A few of them are as follows.
We can check whether physical connectivity is proper or not. The physical connections include switches, cables, hubs, routers, and so on.
We must check whether the device configuration is correct or not. The device configuration includes IP addresses, DNS servers, and so on.
We can check for security issues as well. This includes checking firewalls, MAC address filtering, and so on.
14. What is the difference between protocols and data packets?
The difference between protocols and data packets is as follows.
Protocols: Protocols are defined as rules basis on which the transmission of data and resources takes place between interconnected computer devices.
Data Packets: A data packet can be defined as the basic unit of information. The unit of information can be transferred throughout the network.
15. What is the default gateway in networking?
The default gateway is a device (usually a router) that connects a local network to external networks or the internet. It acts as the exit point for network traffic leaving the local network.
16. What is the function of the MAC address?
A MAC address (Media Access Control) is a unique identifier assigned to network interfaces for communication on a physical network. It helps in identifying devices within a local network.
17. What is the role of DNS in networking?
DNS (Domain Name System) translates human-readable domain names (like google.com) into IP addresses, making it easier for users to access websites.
18. What is the difference between IPv4 and IPv6?
IPv4 uses 32-bit addresses while IPv6 uses 128-bit addresses, allowing for a larger number of unique IP addresses. IPv6 also includes better security and simplified packet headers.
19. What is the purpose of a subnet mask?
A subnet mask defines the network and host portions of an IP address, helping to divide large networks into smaller subnetworks for better management and efficiency.
CCNA Interview Questions for Experienced
20. How is a half-duplex different from a full duplex?
The half-and-full duplex define the modes of communication in networking. The half-duplex allows transferring of data in only one direction at a time. This means that other devices can only receive data while one is transferring and vice versa. Whereas the full duplex allows transferring of data in both directions at the same time. This means that two devices can transfer and receive data at the same time.
21. How switches and hubs are different from each other?
The switch and hub are the devices that are used in networking for connecting devices. A switch can be defined as a hardware device that allows connecting various devices within a network. Whereas a hub can be defined as a device that allows connecting various other devices together in a network.
22. What is the IP address and size of it?
The IP address stands for Internet Protocol address. It helps in identifying and locating any network device. The size of the IP addresses is as follows.
32-bit for internet protocol version 4(IPv4)
128-bit for internet protocol version 6(IPv6).
23. What is the default size of the Maximum Transmission unit for Ethernet networks?
The default size of the maximum transmission unit size for Ethernet networks is 1500 bytes. The maximum size includes header and payload. We can adjust this value accordingly for different network devices. Adjusting MTU size is important as it helps in optimizing the performance of the networks.
24. Which are the first and last layers of the OSI model?
The first and last layers of the OSI model are the Physical layer and the Application layer. The physical layer helps in defining the connection between any device and its transmission medium. This layer consists of voltages, hubs, adapters, and so on. Whereas, the main use of the application layer is that it assures that the application must communicate with other applications very easily. This takes place even in different systems and networks.
25. Define VLAN and its use.
The VLAN stands for Virtual Local Area Network. This network allows connecting more than one device and network that are from different LANs. VLAN is used to group together devices securely. It manages traffic between devices and networks and increases network performance.
26. How are LAN, WAN, and MAN different from each other?
The LAN, WAN, and MAN are different from each other as follows.
LAN: LAN stands for Local Area Network. LAN allows connecting computers and network devices with each other. It allows connecting within the same building.
WAN: WAN stands for Wide Area Network. WAN allows connecting various computer devices. WAN allows connecting computers over large areas.
MAN: MAN stands for Metropolitan Area Network. MAN allows connecting networks widely. The networks can be connected within various buildings but in the same area.
27. What is the meaning of MTU? What is its use?
The MTU stands for Maximum Transmission Unit. It is used during transmission. It allows determining the maximum size of the data packet. The default size of the maximum transmission unit size for Ethernet networks is 1500 bytes. We can adjust this value accordingly for network devices. Adjusting MTU size is important as it helps in optimizing the performance of the networks.
28. How are static, default, and dynamic routes are different from each other?
The static, default, and dynamic routes are different from each other as follows.
Static Route: The static route is a route on which a data packet is required to move in order to reach any particular network.
Default Route: The default route is helpful when there is no exit point. This route especially helps when for an IP packet, the switch is unable to find any match in the routing table.
Dynamic Route: The dynamic route is used to exchange data between routers. This route also helps in finding the optimal ways that network devices can have between them.
29. What are the benefits of VLAN?
There are many benefits of VLAN. A few of them are as follows.
VLAN network is a secured network.
The cost of VLAN is also lower.
Managing VLAN is easy.
The performance of VLAN is good.
30. Which is the fourth layer of the OSI model? And why it is used?
The fourth layer of the OSI model is the transport layer. The main use of this layer is to transfer data. The data is transferred between end users. This layer is built when the IP session for communication begins or ends. The transport layer controls the flow of information and ensures that the information is transferred efficiently and smoothly.
31. What is the difference between the first and second layers of the OSI model?
The first layer of the OSI model is the physical layer. Whereas the second layer of the OSI model is the data link layer.
Physical Layer: The physical layer helps in defining the connection between any device and its transmission medium. This layer consists of voltages, hubs, adapters, and so on.
Data Link Layer: The data link layer allows transferring of data between networks. This transmission takes place by means of functional and procedural. This layer is useful as it can detect errors that may or may not occur in the physical layer. This layer can also correct those detected errors in most cases.
32. What is the use of the application layer?
The application layer is the seventh and the last layer in the OSI model. The main use of this layer is that it assures that the application can communicate with other applications very easily. This takes place even in different systems and networks. While communicating, one application can send files to other applications easily. This layer interacts with all the lower six layers of the OSI model. It checks whether the transmission of information is appropriate or not.
33. What is the role of the fifth layer in the OSI model?
The fifth layer in the OSI model is the session layer. This layer is responsible for controlling and managing the connections between computer systems. The session layer can also terminate the connections between applications. This layer manages the flow and duration of the connection. The session layer also uses a checkpoint mechanism, which is helpful in recovering the information in case of network faults.
34. How is TCP different from UDP?
The differences between TCP and UDP are as follows.
TCP
UDP
The Transmission Control Protocol(TCP) allows the transferring of information between source and destination and guarantees information delivery in the correct order.
The User Datagram Protocol(UDP) allows the transferring of information between source and destination but does not guarantee information delivery and correct order.
In TCP, before the transfer of information, a connection is built between the source and destination.
In UDP, there is no prior connection built between the source and destination.
TCP is slower as compared to UDP
UDP is more speedy and efficient than TCP
TCP checks before transferring a large amount of data from source to destination. To control the flow of too much data.
UDP does not follow any flow control mechanism like TCP.
35. How will you define subnet? What are their uses?
The subnet is the combination of the words sub and network. The sub-network can be defined as subdivided pieces of any large network. The subnet is used to divide domains in order to route traffic efficiently. There are many uses of the subnet. A few of them are as follows.
Subnet improves the performance of the network.
Subnet helps in routing traffic efficiently.
A subnet reduces the load on a network.
36. What do you mean by EIGRP? Mention some metrics of EIGRP Protocol.
EIGRP stands for Enhanced Interior Gateway Routing Protocol which is a dynamic routing protocol that is used to find the best path between the two-layer 3 devices so that the packet can be delivered. Here are some metrics of the EIGRP protocol:
Bandwidth: The capacity of a link in kilobytes per second (kbps)
Load: This represents the current load of the link; the value of the load can be varied from 0 to 255
Delay: Delay represents the time a packet will take to traverse the link
Reliability: It represents the reliability of the link
MTU: MTU stands for Maximum Transmission Unit
In the above metric, bandwidth, and load are used by default.
CDP stands for Cisco Discovery Protocol is a layer 2 Cisco network protocol that helps in inspecting the devices connected to the network efficiently. Here are some functions of CDP:
CDP assists in troubleshooting TPV(Type Length Values) fields
CDP also detects the IP address of a wrongly configured switch/router on the other side of a WAN link.
CDP allows the use of RTP (Real-Time Transport Protocol) and different network-layer protocols to locate the devices and tell how they are configured.
CDP also contains the version of IOS software and hardware capabilities.
38. What do you mean by a broadcast domain and a collision domain?
A broadcast domain is a scenario that can be created when devices send a broadcast message; all the other devices which are included in the broadcast have to pay attention to it.
A collision domain is a scenario that can be created when a device sends out a message to the network; all other devices which are included in its collision domain have to pay attention to it.
39. Explain BootP.
BootP stands for Bootstrap Protocol which is a network protocol that can be used by the networking administration to give IP addresses to a member of that network for participating with other networking devices by the main server.
40. What do you mean by route poisoning?
Route Poisoning is a method that basically prevents a network from sending the data packets to a path destination that has already become invalid. Routing Protocol is done when Distance Vector Routing Protocol sees an invalid router.
41. What is NAT, and why is it used?
NAT (Network Address Translation) is used to map private IP addresses to a public IP address, allowing multiple devices on a local network to access the internet using a single public IP.
42. What is the difference between static and dynamic routing?
Static routing involves manually configuring routes, while dynamic routing automatically updates routing tables based on network changes using protocols like RIP, OSPF, or EIGRP.
43. What is VLAN trunking?
VLAN trunking allows multiple VLANs to share a single network link, enabling efficient data transfer between different VLANs through Trunk Ports.
44. What is the purpose of the ARP protocol?
ARP (Address Resolution Protocol) maps an IP address to its corresponding MAC address, enabling devices to communicate on a local network.
45. What is the difference between TCP and UDP?
TCP is connection-oriented, reliable, and ensures data delivery.
UDP is connectionless, faster, but does not guarantee delivery.
Frequently Asked Questions
What are the 3 modules of CCNA?
There are a total of three modules of CCNA, which are the following: first is, Introduction to Networks; second is, Enterprise Networking, Security and Automation, and third is, Switching, Routing, and Wireless Essentials.
Which CCNA is current?
There is only one single CCNA exam, and the latest exam's code is 200-301 CCNA. Here are some of the core topics of this version: Network Fundamentals, Network Access, IP Connectivity, IP Services, Security Fundamentals, etc.
What are CCNA types?
CCNA has various specializations, such as CCNA Routing and Switching, CCNA Security, and CCNA Data Center, catering to different aspects of networking.
Does CCNA require coding?
CCNA primarily focuses on networking concepts and configurations, not coding. However, a basic understanding of scripting languages like Python can be beneficial for network automation tasks.
Conclusion
In this article, we have discussed about CCNA interview questions. This blog of CCNA Interview Questions serves as a valuable resource for individuals aspiring to excel in networking interviews. Covering a spectrum of topics, from fundamental networking principles to Cisco device configurations, these questions offer insights into the diverse skills demanded by the CCNA certification. To learn more, you can check out our other articles:
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