[2026] Top 10 CCNA Interview Questions

Key takeaways

• Subnetting is the question that separates prepared candidates, so practise splitting a /24 into equal subnets by hand.
• Know the difference between what a switch does at Layer 2 and a router does at Layer 3 before the interview.
• For OSPF and NAT, explain the problem each one solves before describing how it works.

A career in networking often starts with the Cisco Certified Network Associate (CCNA) certification. As part of the certification journey or during job interviews, you might encounter a variety of questions that test your knowledge and skills in network fundamentals, routing and switching, and more. Here are the top 10 CCNA interview questions that are commonly asked, with clear and concise answers to help you prepare.

1. What is the OSI model, and what are its layers?

Answer: The OSI (Open Systems Interconnection) model is a conceptual framework used to understand and implement networking protocols. It consists of seven layers: 1) Physical, 2) Data Link, 3) Network, 4) Transport, 5) Session, 6) Presentation, and 7) Application. Each layer serves a specific function in network communication.

2. Explain the difference between a switch and a hub.

Answer: A switch operates at the Data Link layer and can intelligently forward data packets to specific devices on a network based on MAC addresses. A hub, on the other hand, operates at the Physical layer and broadcasts data packets to all devices on a network, which can lead to inefficiencies and network congestion.

3. What is a VLAN, and why is it used?

Answer: A VLAN (Virtual Local Area Network) is a logical grouping of devices within a network that behave as if they are on the same physical network, regardless of their actual location. VLANs improve network efficiency and security by isolating traffic and reducing broadcast domains.

4. Describe the purpose of the show ip interface brief command.

Answer: The show ip interface brief command provides a quick overview of the status and IP configuration of all interfaces on a Cisco router or switch. It displays each interface’s IP address, status (up or down), and protocol status, aiding in network troubleshooting and configuration verification.

5. What is the function of the Spanning Tree Protocol (STP)?

Answer: STP is used to prevent loops in Ethernet networks by creating a loop-free logical topology. It automatically disables redundant paths and reactivates them if the primary path fails, ensuring network stability and avoiding broadcast storms.

6. How does the ping command work, and what does it test?

Answer: The ping command sends ICMP Echo Request packets to a specified IP address and measures the round-trip time for the packets to reach the destination and return. It is used to test connectivity between devices and diagnose network issues.

7. What is the difference between static routing and dynamic routing?

Answer: Static routing involves manually configuring routes in a network, while dynamic routing uses routing protocols like OSPF or EIGRP to automatically discover and maintain routes. Static routing requires manual updates, whereas dynamic routing adapts to network changes automatically.

8. Explain the concept of NAT (Network Address Translation).

Answer: NAT is a technique used to translate private IP addresses within a local network to a single public IP address for communication with external networks. It helps conserve public IP addresses and adds a layer of security by hiding internal IP addresses.

9. What is a subnet mask, and how does it work?

Answer: A subnet mask is used to determine the network and host portions of an IP address. It works by masking the IP address to separate the network bits from the host bits, enabling devices to determine whether an IP address is within the same network or a different one.

10. How do you configure a basic static IP address on a Cisco router?

Answer: To configure a static IP address, enter global configuration mode, select the interface with interface [interface_name], and use the command ip address [IP_address] [subnet_mask]. For example, interface GigabitEthernet0/1 followed by ip address 192.168.1.1 255.255.255.0 assigns the IP address 192.168.1.1 with a subnet mask of 255.255.255.0.

Conclusion:

Preparing for a CCNA interview involves understanding key networking concepts and being able to articulate your knowledge effectively. The top 10 questions listed here cover fundamental topics that are frequently addressed in interviews. By familiarizing yourself with these questions and their answers, you’ll be well-equipped to demonstrate your expertise and tackle your CCNA interview with confidence.

Related reading

• [2026] CCNA Certification Exam Questions
• [2026] CCNA Job Interview Questions
• [2026] CCNA Interview Questions PDF