CCNA Interview Questions 2024-25

Table of Content

• Introduction
• What is a network?
• What is the OSI model? Can you explain the layers?
• Differentiate between a hub, a switch, and a router.
• What are the differences between TCP and UDP?
• What are private IP addresses?
• What do you mean by VLAN? How does it work?
• What purpose does the default gateway have?
• What is subnetting, and why is it used? 
• What is the difference between a static and dynamic IP address?
• Explain the difference between routing and switching.
• Explain broadcast and collision domains.
• What is NAT and explain its use briefly.
• What are ACLs?
• Differentiate between distance vector and link-state routing protocols.
• What is a MAC address, and is it different from an IP address?
• What is the difference between half and full duplex communication?
• What is OSPF, and how does it work?
• What is STP  and why is it important?
• Explain the difference between IPv4 and IPv6.
• What is HSRP (Hot Standby Router Protocol)
• Conclusion

Introduction

CCNA or Cisco Certified Network Associate prepares you for modern networking and Innovative Academy prepares you for technical and theoretical rounds of interview. It enables network engineers to work not only on Cisco systems but almost all the systems.

1. What is a network?
   A network is a collection of computers and devices connected to share resources, such as files, printers, and internet access.
   
2. What is the OSI model? Can you explain the layers?
   The OSI (Open Systems Interconnection) model is a conceptual framework used to understand and implement standard protocols in seven layers:
   1. Physical
   2. Data Link
   3. Network
   4. Transport
   5. Session
   6.  Presentation
   7. Application

3. Differentiate between a hub, a switch, and a router.
   Hub: Broadcasts data to all ports.
   Switch: Forwards data to specific devices (based on MAC addresses)Router: Responsible for routing data between different networks (based on IP addresses)

4. What are the differences between TCP and UDP?
   TCP (Transmission Control Protocol) is connection-oriented and guarantees data delivery while UDP (User Datagram Protocol) is connectionless and does not guarantee delivery, but is faster.

5. What are private IP addresses?
   Private IP addresses are non-routable IP addresses used within a local network. Examples:
   10.0.0.0 – 10.255.255.255
   172.16.0.0 – 172.31.255.255
   192.168.0.0 – 192.168.255.255

6. What do you mean by VLAN? How does it work?
   A VLAN (Virtual Local Area Network) divides a physical network into many logical networks, allowing devices from different VLANs to communicate as if they were on separate networks. 
   
7. What purpose does the default gateway have?
   A default gateway is a device (generally a router) that routes traffic from a local network to destinations outside the network, such as the Internet.

8. What is subnetting, and why is it used?
   Subnetting divides a larger network into smaller sub-networks to improve efficiency, reduce network traffic, and enhance security.
   
9. What is the difference between a static and dynamic IP address?
   A static IP is manually assigned and remains constant. A dynamic IP is assigned by DHCP (Dynamic Host Configuration Protocol) and may change over time.

10. Explain the difference between routing and switching.
    Routing moves data between different networks while switching operates within a network by forwarding data based on MAC addresses.
    
11. Explain broadcast and collision domains.
    The broadcast and collision domains are network segments where a broadcast is propagated and data packets can collide respectively.

12. What is NAT and explain its use briefly.
    NAT or Network Address Translation translates private IP addresses to public IP addresses and public to private, allowing multiple devices on a local network to share a single public IP.
    
13. What are ACLs?
    ACLs (Access Control Lists) are filters that control which packets are allowed or denied access to a network based on predefined rules (e.g., source/destination IPs, protocols).
    
14. Differentiate between distance vector and link-state routing protocols.
    Distance Vector uses the distance to a destination network to determine the best path (e.g., RIP).On the other hand, the link state uses a complete view of the network topology to determine the best path (e.g., OSPF).
    
15. What is a MAC address, and is it different from an IP address?
    A MAC (Media Access Control Address) address is a hardware address used to identify devices on a local network. An IP (Internet Protocol Address) address is a logical address used to identify devices across networks.
    
16. What is the difference between half and full duplex communication?
    Half-duplex: Data transmission can occur in both directions, but not simultaneously.
    Full-duplex: Data transmission can occur in both directions simultaneously.

17.  What is OSPF, and how does it work?
    Open Shortest Path First (OSPF) is a link-state routing protocol that uses the shortest path algorithm to determine the best route between routers.
    
18. What is STP  and why is it important?
    STP(Spanning Tree Protocol) averts loops in a network by blocking redundant paths in a switching topology, ensuring a loop-free logical topology.

19. Explain the difference between IPv4 and IPv6.
    IPv4 uses 32-bit addresses (e.g., 192.168.0.1), allowing for about 4.3 billion unique addresses IPv6 uses 128-bit addresses (e.g., 2001:0db8::1), providing an exponentially larger number of unique addresses.

20. What is HSRP (Hot Standby Router Protocol)?
    
    Ans.HSRP is a Cisco protocol that provides high network availability by routing traffic to backup routers if the primary router fails.
    

Conclusion

Thus, by going through the above blog, you would get a basic idea about what are the most asked questions for the Network Engineer Interview for CCNA currently, helping you prepare for the same.