Top Cisco Interview Questions and Answers for 2024

With the right preparation, the chances of succeeding in your cisco job interview become significantly high. This blog is designed to help applicants nail Cisco interviews. No matter whether you are fresher, mid-level, or highly experienced, you will get top cisco interview questions and their most relevant answers in this blog.

Hundreds of candidates face Cisco interview questions every year. The skillset required is tested through individual interviews for experienced candidates and mass campus recruitment drives for freshers. Candidates with good knowledge of networking concepts, computer intelligence, and strong analytical skills can ace the Cisco interview.

In addition, you can take up a Cisco certification course to build strong fundamentals in networking concepts and to better understand Cisco technical interview questions. Your expertise in algorithms, data structures, programming languages (like C and C++, and scripting languages (like JavaScript and Python) may also maximize your chances of landing a Cisco job.

Learn all about Cisco Certifications, their benefits, and their scope; read our blog – What are Cisco Certifications?

Table of Contents

• Cisco Interview Process
• Cisco Interview Questions and Answers for Fresh Graduates
• Cisco Interview Questions for Experienced Candidates
• HR Round Questions and Answers for Cisco Interview Process

Before we begin with Cisco interview questions and answers, let’s look at the Cisco interview process.

Cisco Interview Process

The Cisco interview process for various roles may include networking interview questions, coding and Cisco technical interview questions. These check the in-depth knowledge and capability of the candidate for the role they have applied for. An individual should thoroughly prepare for Cisco networking interview questions and answers because Cisco interviews are difficult to crack. The good news is that preparing in advance can make a big difference. The Cisco interview process is categorized into 3 rounds:

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Round 1: Online Assessment Test

The online assessment test includes questions related to aptitude and technical aspects. The aptitude test covers Profit & Loss, Probability, Algebra, Percentage, Permutation and Combination, Algebra, Number series, Simple and Compound Interest, etc.  Apart from aptitude, the technical questions related to Algorithms, C language, Computer Networking, Data electronics, and MCQs on various topics such as OS (virtual memory, threads, memory management), Linux threads, Linked Lists, IPCs, mutex locks are also covered. 

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Round 2: Technical Interview 2

It includes Cisco interview questions (technical) related to networking, such as hub vs switch, the significance of gateway, how to build a packet when it goes from one network to another, how to route a packet from one network to another, and bit manipulation algorithms.

Round 3: HR Round

The HR interview round takes around 40-50 minutes. HR will ask you about the role, why you want to switch jobs, the most critical bug you have solved, and why Cisco? HR may also ask questions about your resume. You need to be well-prepared before this round and have a good knowledge of Cisco, your resume, and the field from which you have graduated.

Cisco Interview Questions and Answers for Fresh Graduates

We have listed the 25 top Cisco interview questions for freshers to prepare thoroughly for their upcoming Cisco interview. If you are a fresher and this is your first interview, prepare the below questions and answers for your technical round in a Cisco interview.

Q1. What is a link?

Ans. A link is a physical or logical component of a network that interconnects devices or nodes.

Q2. What is a node?

Ans. A node is a connection point within a network for systematic data transmission. A computer or printer or any other type of device capable of sending and receiving data through a network can be called a node.

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Q3. What is Firewall?

Ans. A firewall is a network processing device that monitors and filters the data, both incoming and outgoing and provides security based on the already defined security policies. A firewall protects your computer or network from malicious or unnecessary traffic from outside cyber attackers.

Q4. What is routing?

Ans. Routing is establishing the routes that data packets take on their way to a particular destination. Routing is done with a router, a device used to select a path for traffic in a network or between or across multiple networks. This network topology depends on a setup of hardware to effectively relay data.

Q5. What is the purpose of the data link layer in the TCP/IP or OSI layer?

Ans. The Data-Link layer is responsible for transporting data within a network. The Data-link layer packages the higher-layer data into frames. This packaging process is referred to as framing or encapsulation. The data-Link layer has 2 sublayers:

• Logical Link Control (LLC) sublayer
• Media Access Control (MAC) sublayer

Q6. What are the key advantages of using switches?

Ans. Switches interpret the bits in the received frame so that they can typically send the frame out of the one required port rather than all other ports. They don’t create a single shared bus-like hub.

Q7. When does network congestion occur?

Ans. Network congestion happens when applications send more data than the network devices (e.g., routers and switches) can handle or accommodate. Thereby causing buffers on these devices to fill up and sometimes overflow.

Here, a buffer is a portion of a device’s memory set aside as a temporary holding place for data. This data is sent to or received from other devices, and the whole process might result in delayed or lost packets. Eventually, applications retransmit the data and end up adding more traffic. This further increases congestion.

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Q8. What is a ‘Window’ in networking terms?

Ans. A window is a method of controlling the flow of packets between two network hosts or computers. In a network, the receiving system sends window ” announcements ” to the transmitting system. It is a way of acknowledging data receipt to inform the current buffer size of the transmitting system.

For instance, when the window size is reported as zero, transmitting systems should wait for an acknowledgement to send the next chunk of data. When the receiving system reports a larger buffer size than a single data packet, the transmitting system can send multiple chunks of data before waiting for an acknowledgement.

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Q9. What are the two flags used in the core handshake of a typical TCP connection establishment?

Ans. The two flags used in the core handshake of a typical TCP connection establishment are SYN and ACK.

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Q10. Which layer identifies and establishes the availability of the Intended Communication Partner?

Ans. The application layer identifies and establishes the connection with the Intended Communication partner.

Q11. What are the features of an IP access list?

Ans. There are three different kinds of access lists. These are standard, extended, and named. The benefits of IP access lists include the following:

• Authenticate incoming rsh and rcp requests
• Block unwanted traffic or users
• Control access to vty
• Identify or classify traffic for QoS features
• Limit debug command output
• Provide bandwidth control
• Provide NAT control
• Reduce the chance of DoS attacks
• Restrict the content of routing updates
• Trigger dial-on-demand calls

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Cisco Interview Questions for Experienced Candidates

The Cisco interview process for experienced candidates generally follows an established company pattern. Typically, Cisco ASA interview questions are asked in this round. Also, there are high chances that experienced professionals may face challenging technical interview questions. Therefore, below are Cisco networking interview questions and answers experienced candidates may face in an interview.

Q12. What is the access-list range for extended IP, extended XNS, and extended VINES?

Ans. For Cisco devices,

• The extended IP access list range is 100–199 and 2000–2699.
• Extended XNS access-list range is 500–599.
• The extended VINES access-list range is 101–200.

Q13. How will you use a linked list to simulate 3 TCP/IP packets?

Ans. To use a linked list to simulate 3 TCP/IP packets, all the packets should have a source IP, a destination IP, and some data (at least 20 characters).

• Step 1: We need to search the packets individually for suspicious IP (that starts with 000).
• Step 2: We will then check the data for cipher, and subtract 1 from ASCII of first 8 to see if “JOHN JAY” is the data.
• Step 3: Our program should ideally simulate processing six packets in 2 groups of 3.
• Step 4: Then we have to check all 3 packets (or nodes), change the IP and data in each one, and check again. Instead of a linked list, a QUEUE can be used, provided the QUEUE contains the same data.

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Q14. How is a TCP connection made?

Ans. A TCP connection is made as follows:

• Step1: Sender and receiver synchronize so that a connection is made. The operating systems at both ends stay informed that a connection is established.
• Step2: Then the sender starts transmitting data. It also gets acknowledgements. A timer is started as soon as the sender starts sending data.
• Step3: If the sender has not received any acknowledgement even after the timer exceeds its limit, it retransmits the data.
• Step4: In the case of windowing, if the buffer on the receiver is full, the receiver sends a stop signal to the sender. The sender stops transmitting data.
• Step5: After processing all data, the receiver sends a go signal to the sender. Then, the sender starts transmitting data again. This is the case with windowing.

Q15. What is a firewall, and the security level of an ASA firewall?

Ans. A firewall is a layer or device between a trusted and an untrusted network. Its function is to deny or permit traffic access travelling into and out of the network. So, it is a protective layer that blocks unauthorized access by users on both sides of the firewall.

ASA Firewall Security Level can be 0-100. 100 is the highest security level on an ASA firewall, representing the most trusted Zone. On the other hand, 0 is the lowest security level on an ASA Firewall.

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Q16. What is the Cisco default TCP session timeout?

Ans. TCP session timeout for Cisco is 1 minute. The connection slots are freed approximately 60 seconds after a normal connection close sequence. This can be configured to some other setting as per requirement. A global idle timeout duration can be set for various protocols’ connection and translation slots. Resources get returned to the free pool if slots are not used for idle times specified. 

Q 17. What are various OSI layers?

OSI model comprises the following seven layers-

1. Physical Layer
2. Data Link Layer
3. Network Layer
4. Transport Layer
5. Session Layer
6. Presentation Layer
7. Application Layer

Q18. What is a transparent firewall?

Ans. A transparent firewall acts as a line of the layer between 2 devices. Transparent firewalls easily deploy existing networks. Transparent firewalls also let in layer 3 traffic from higher to lower security levels without access lists.

Q19. Which LAN switching method is used in Cisco Catalyst 5000?

Ans. Cisco Catalyst 5000 uses the store-and-forward switching method. The entire frame gets stored in buffers, and a CRC check is performed before deciding whether or not the data frame should be forwarded.

Q20. What are the different memories used in a Cisco router?

Ans. There are 3 types of memories in a Cisco router:

1. NVRAM – to store the startup configuration file
2. DRAM – to store the configuration file which gets executed
3. Flash Memory – to store Cisco IOS

Q21. Explain how cut-through LAN switching works.

Ans. Cut-through LAN switching – when the router receives a data frame, it immediately sends it out again and forwards it to the next network as soon as it reads the destination address.

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Q22. How would you explain an IP address to a layman?

Ans. Every machine connected to the Internet has a unique number assigned to it. This is an IP address. Without this unique number or tag on your machine, you cannot communicate with other users, computers, and devices on the Internet.

In other words, the IP address is like a telephone number, as it is unique and identifies a way to reach you exclusively.

Q23. What is recovery testing?

Ans. Recovery testing is a software testing technique.  It tells how well the software can recover from software/hardware crashes, network failures, etc.

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HR Round Questions and Answers for Cisco Interview Process

Once you clear Cisco interview questions (technical), the next and probably final round occurs with HR. The HR Round more or less covers the same group of questions that are asked for other jobs as well. The answer, however, may differ on an individual basis for these questions. So, these answers have been focused on answering them so that you get more points. Read on.

Q24. Any particular reason for leaving your current job?

Ans. I believe I am ready for a new stage and newer challenges in my career. I would like to continue growing as well as learning from my field. And I have never been this confident about taking up more tasks and additional responsibilities. I don’t get too many complex opportunities to tackle in my current job role, especially those related to protocols like OSPF, EIGRP, BGP, and UDP. So, I am sure this role will allow me to handle them.

Q25. Why do you want to join this company?

Ans. Yours is a reputed organization and a global leader in high-end technology products and services. I truly admire this company’s rich value-driven work culture. Besides, I am a huge fan of the present CEO. I learned that he started his career as a software developer at a small firm. Moreover, the career graphs of your senior leadership team members are highly motivating. They signify that anyone ready to work hard and remain persistent can easily grow in this organization.

Q26. Did you apply for a position at some other company? Or What other companies are you interviewing with?

Ans. I am still at a very early stage of my job search. I’ve applied for several openings, but this position seems the most exciting. This job description fits my skill sets and knowledge well. Besides, I haven’t received a call from any other organization as good as this yet.

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Q27. Do you have any prior experience as a network engineer?

Answer for a fresher: I only completed my Bachelor’s degree in Btech this year. Being a fresher, I do not have any prior professional experience related to Cisco and networking technologies. Still, I would like to add that I was a Student Network Engineer in my college computer lab. I have also done 2 internships in this field and possess freelance experience as a backend developer. Also, I am in the process of completing my CCNA certification by next month.

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Answer for an experienced candidate: I am a Microsoft Certified Solutions Expert with 2.5 years of relevant experience as a network engineer. I started my career as a help desk support officer. Due to a lack of challenges on the job, I had to switch over to Cisco and networking. Today, I am in love with what I do for a living as a networking engineer. Every single day brings forth newer opportunities to learn at work. From these challenges, I get to pick up the latest technology. I would like to add that I completed the Cisco Certified Network Associate (CCNA) and Cisco Certified Network Professional (CCNP) certifications last year.

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Conclusion

This top Cisco interview questions and answers guide will help you prepare for your upcoming Cisco interview and face the questions confidently. We have covered Cisco interview questions for freshers and experienced professionals both. Also technical as well as Cisco networking interview questions and answers are also discussed in this blog. You can take up a Cisco certification or course to add more weight to your resume.

Alternatively, you may consider an online Networking and Hardware course to grow your knowledge. Successfully completing a certification or course in networking and preparing with the Cisco interview questions and answers in this article will help you stand out as a strong potential candidate for the job.

All the best!