Everything about CCNA Router and Switch Interview Questions: A Complete Guide

The Cisco CCNA certification would surely give you more confidence in taking the big step toward a glorious life in Network Infrastructure. CCNA stands for Cisco Certified Network Associate, and it is a good, solid foundation for building a career under the title of a Network Engineer.

A CCNA certification should really work for you, whether you come from a Desktop Support background... 

This guide explores routing and switching interview questions for beginners, intermediates, and advanced candidates and evaluates their chances for success. 

CCNA Routing and Switching Interview Questions For Freshers

1. What do you understand by Networking?

Networking is a collection of computers that communicate and share information. Connecting devices or systems so that they are able to share resources is called networking.

Types of computer networks:

• Local Area Network (LAN); it covers a small area, like an office or home.

• Wide Area Network (WAN); this type covers large geographical areas such as the Internet.

• Metropolitan Area Network (MAN:; network covering a city or a large campus.

• Personal Area Network (PAN); interconnects personal devices with each other, usually within the range of Bluetooth.

Key Concepts in Networking:

• IP Addressing: Assigns unique addresses to devices within a given network. 

• Routing: Selecting the path for sending data.

• Protocols: Set of rules to control communication among devices, e.g., TCP/IP, HTTP, etc. 

• Topology: Arrangement of physical and logical interconnection in a network.

 2. What is a routing protocol and its functions?

A routing protocol is a set of rules and algorithmic guidelines by which routers communicate and force to determine the most effective path for data flow.

Common Routing Protocols are:

• RIP: A protocol that measures in hop counts.

• OSPF: Shortest path based on link costs.

• BGP: Routing between autonomous systems.

• EIGRP: Cisco routing protocol with the best of distance vector and link state.

Functions of routing protocols:

• Calculate the best path based on metrics such as hop count, bandwidth, and transfer delay.

• Update routing tables when any changes occur in the network.

• Create and exchange routing information with every router.

• Prevent routing loops.

3. Difference Between a Router and a Switch

• Routers operate on Layer 3 (Network Layer) while switches work on Layer 2 (Data Link Layer).

• Routers forward packets between different networks using IP addresses; switches forward packets within the same network using MAC addresses.

• Routers determine the best path for data to travel; switches connect hardware devices that reside within the same network." 

4. What are VLANs and why are they used?

VLANs, short for Virtual Local Area Networks, are used to group devices that may physically be separated but behave logically as being part of the same network.

VLANs offer many advantages:

• By separating traffic, it increases security.

• By limiting broadcast traffic.

• By grouping networks by department or project.

• It proves to be an easy-to-use network management. tool

• It optimizes network performance.

5. What is the function of ARP?

The Address Resolution Protocol is responsible for the conversion of the IP address into the MAC address. When a device wants to communicate locally, it sends an ARP broadcast asking who has the IP MAC address. The one with such an IP will respond with its MAC. 

6. What Does Default Gateway Mean?

Basically, a default gateway is the router interface to which all devices shall send packets that are not intended to be delivered in its local network. Without it, communication is possible only within the Local area network.

7. Differences Between Static Routing and Dynamic Routing

• Static routes are determined manually, while dynamic routes are learned automatically through predefined protocols.

• Static route is a poor choice when it comes to network failure; dynamic routing would update the routes to the new path as per network changes.

• Static is simple, but it offers no scaling opportunities; dynamic routing will offer scaling opportunities, and the efficiency is comparatively higher.

8. What Does Spanning Tree Protocol Do?

In a switched network, it provides a loop-free topology while ending the broadcast storm and congestion handling by blocking some redundant links, while maintaining a loop-free topology, around which the system can change automatically.

9. What is DHC, P, and how does it work?

Dynamic Host Configuration Protocol (DHCP) is the protocol that dynamically assigns IP addresses and network parameters to hosts on the network.

The process consists of DORA:

• Discover: The client requests an IP address.

• Offer: Server provides an available IP.

• Request: The client requests the provided IP.

• Acknowledgment: The server confirms the assignment.

10. Explain ACLs and Why They Are Significant.

Access Control Lists (ACLs) filter network traffic according to set rules such as IP addresses, ports, or protocols.

ACLs are used for:

• Increasing network security.

• Restricting access to sensitive resources.

• Enforcing network policies.

• Prioritizing certain traffic.

CCNA Routing and Switching Interview Questions for Experts

11. Differences between Distance Vector and Link-State Protocols

• Distance vector protocols inform only neighboring routers; link-state protocols keep the full network topology.

• Distance vector protocols use a simple metric like hop count; link-state protocols independently calculate the shortest paths.

• Distance vector protocols are suitable for small networks; link-state protocols are suitable for large networks with fast convergence.

12. When STP sends a frame over a switch port, how does it prevent a loop?

STP elects a root bridge using the lowest bridge ID (priority + MAC). Ports are assigned states: Root Port - Best path to the root bridge. Designated Port - Best path on a segment to forward traffic. Blocked Port - Prevents loops.

This makes sure that only one logical path is active, preventing broadcast storms.

13. How do VLANs enhance security and performance? Types of VLANs

VLANs isolate traffic and lessen the broadcast load.

Types:

• Data VLAN: User-generated traffic.

• Voice VLAN: Gets precedence over voice traffic.

• Management VLAN: For managing network devices.

• Native VLAN: Carries untagged traffic.

14. Routing Tables and Packet Forwarding

Routing tables contain information concerning all the networks in the organization and their best paths.

Routing tables are those that routers will use to forward packets to the next-hop IP address.

If no route exists, the packet is usually sent to the default gateway or simply discarded.

15. Which Are the Kinds of Switching Techniques?

Store-and-Forward: Checks entire frame for errors before forwarding; high error detection but higher latency. Cut-Through: Forwards frame as soon as destination MAC is read; low latency, but errors may pass.

Fragment-Free: Reads first 64 bytes for collisions before forwarding; balance between latency and error checking.

16. Advantages and Disadvantages of Static vs. Dynamic Routing?

Advantage of static routing: It is simple, safe, and predictable. Disadvantages of Static Routing: Manual installation and not adaptable, with limited scalability. Automatic adaptation in dynamic routing: scales, reduces admin work.

Complexity, consuming resources, and security risks. Disadvantages of Dynamic Routing: Adaptability itself spawns problems. 

17. OSPF Operates Change in Networks

• A link-state database of the network is maintained by OSPF.

• Whenever a link fails, LSAs are flooded to routers in that area.

• The routers replace their databases and recompute the shortest paths, leading to fast convergence.

18. The Dimensions of Collision Domain and Broadcast Domain

• A collision domain is where devices compete for the same transmission medium.

• The broadcast domain is where all devices receive broadcast packets.

• Reducing collision domains involves switches. 

• The routers or VLANs separate broadcast domains. 

19. Purpose of QoS 

Quality of Service prioritizes important traffic like voice and video. Traffic classification, queueing, congestion avoidance, and shaping/policing are ways to implement this.

20. Functions of First Hop Redundancy Protocols (HSRP, VRRP, GLBP): 

Thus, First Hop Redundancy Protocols enable a user to gain access to a redundant default gateway. 

In the event of failure on the active router, standby routers take over, thereby reducing downtime. 

HSRP: Cisco-owned VRRP: Open standard. GLBP: Cisco protocol with load balancing between routers.

Conclusion

Routing and switching are the backbone of modern networking systems. Whether you have just begun or are preparing for advanced certifications, mastering these CCNA concepts is extremely important for an aspiring Network or Security Engineer.

But knowing the theory is not enough; recruiters chase people who can apply that knowledge in real-world environments.

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Be it beginner or advanced, NWKINGS provides the planned, practical guidance that prepares aspiring networking professionals to conquer the industry challenges.

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