Top Cisco Interview Questions and Answers

Are you preparing for your Cisco interview? If so, you’ve come to the right place. In this comprehensive article, we’ll explore some of the most commonly asked Cisco interview questions, covering a wide range of topics from networking fundamentals to specific Cisco technologies and products.

Cisco is a leading global technology company that designs, manufactures, and sells networking equipment, software, and services. With its vast product portfolio and widespread adoption across various industries, Cisco interviews can be challenging and require a solid understanding of networking concepts and hands-on experience.

To help you ace your Cisco interview, we’ve curated a list of questions and answers from the archives of GeeksforGeeks, a trusted online resource for computer science and programming knowledge.

Networking Fundamentals

1. What is the OSI (Open Systems Interconnection) model, and how does it relate to networking?

The OSI model is a conceptual framework used to describe the functions of a networking system. It consists of seven layers, each with specific responsibilities:

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

Understanding the OSI model is crucial for networking professionals as it helps in troubleshooting, designing, and implementing network solutions.

1. Explain the difference between a hub, a switch, and a router.

• Hub: A hub is a simple networking device that connects multiple devices together in a single network segment. It broadcasts all incoming data packets to all connected devices, regardless of their intended destination.
• Switch: A switch is a more intelligent networking device that forwards data packets between connected devices based on their MAC addresses. Switches create separate collision domains for each port, improving network performance and security.
• Router: A router is a networking device that forwards data packets between different networks or network segments. It uses logical addresses (IP addresses) to determine the best path for data transmission and can connect multiple networks, such as LANs and WANs.

1. What is the purpose of the TCP/IP model, and how does it differ from the OSI model?

The TCP/IP (Transmission Control Protocol/Internet Protocol) model is a set of communication protocols used to interconnect network devices on the internet and other computer networks. Unlike the OSI model, which is a conceptual framework, the TCP/IP model is a practical implementation of networking protocols.

The TCP/IP model consists of four layers:

• Application Layer
• Transport Layer
• Internet Layer
• Network Access Layer

While the OSI model is a more comprehensive reference model, the TCP/IP model is simpler and focuses specifically on the protocols used in the internet and other TCP/IP-based networks.

Cisco Technologies and Products

1. What is the difference between a Cisco switch and a Cisco router?

A Cisco switch is a networking device used to connect multiple devices within a single network or LAN (Local Area Network). It operates at the data link layer (Layer 2) of the OSI model and forwards data packets based on MAC addresses. Switches are used to create separate collision domains, improving network performance and security.

On the other hand, a Cisco router is a networking device that interconnects multiple networks or network segments. It operates at the network layer (Layer 3) of the OSI model and forwards data packets based on IP addresses. Routers are used to connect LANs to WANs (Wide Area Networks) and provide features like routing, traffic management, and security.

1. What is the purpose of the Cisco IOS (Internetwork Operating System)?

The Cisco IOS (Internetwork Operating System) is a proprietary operating system developed by Cisco Systems for its networking devices, such as routers, switches, and wireless access points. It provides a common platform for managing and configuring Cisco networking equipment, enabling various network services and applications.

The Cisco IOS offers features like routing protocols, quality of service (QoS), network security, and management tools. It allows network administrators to configure, monitor, and troubleshoot Cisco devices through a command-line interface (CLI) or graphical user interface (GUI).

1. What is the role of VLAN (Virtual Local Area Network) in a Cisco network?

A VLAN (Virtual Local Area Network) is a logical subdivision of a single physical LAN, allowing network administrators to create separate broadcast domains within the same network infrastructure. VLANs provide several benefits, including:

• Improved network performance: By separating broadcast domains, VLANs reduce unnecessary network traffic and improve overall network performance.
• Enhanced security: VLANs can be used to isolate sensitive or critical resources from the rest of the network, enhancing security and access control.
• Flexibility and scalability: VLANs allow for easier network management and scalability by logically grouping devices based on requirements, rather than physical location.

Cisco switches support VLANs and provide various configuration options, such as port-based VLANs, protocol-based VLANs, and VLAN trunking protocols (e.g., IEEE 802.1Q).

1. What is the purpose of the Cisco Unified Communications Manager (CUCM)?

The Cisco Unified Communications Manager (CUCM), formerly known as Cisco CallManager, is a software-based IP Private Branch Exchange (IP PBX) system used for managing and controlling voice and video communications in an IP network. It is a core component of Cisco’s Unified Communications solution.

The primary functions of the CUCM include:

• Call processing and routing
• Voice mail and automated attendant integration
• Presence services
• Video conferencing and collaboration
• Integration with desktop applications and mobile devices

The CUCM provides a centralized platform for managing and deploying various unified communications services, enabling organizations to streamline their communication infrastructure and enhance collaboration across different devices and locations.

1. What is the purpose of the Cisco Wireless LAN Controller (WLC)?

The Cisco Wireless LAN Controller (WLC) is a hardware and software solution that centrally manages and controls Cisco wireless access points (APs) in a wireless network infrastructure. It acts as the central control point for configuring, managing, and monitoring wireless access points and wireless clients.

The primary functions of the Cisco WLC include:

• Centralized management of wireless access points
• Wireless client authentication and security
• Radio resource management (RRM) and RF (Radio Frequency) optimization
• Quality of Service (QoS) enforcement
• Wireless intrusion prevention and detection

By centralizing the management and control of wireless access points, the Cisco WLC simplifies the deployment and administration of large-scale wireless networks, providing a consistent user experience and enhancing overall network security and performance.

These are just a few examples of the many Cisco interview questions you may encounter. It’s essential to have a solid understanding of networking concepts, Cisco technologies, and hands-on experience to effectively answer these questions and demonstrate your expertise during the interview process.

Remember, preparation is key. Familiarize yourself with the latest Cisco products, technologies, and best practices. Additionally, practice answering questions out loud and consider seeking guidance from experienced Cisco professionals or mentors to further enhance your readiness for the interview.

Good luck with your Cisco interview!