Top CCNA Interview Question/Answer

CCNA Important Question / Answer

Q1. What is a ‘router’?
Ans. A router is a device that forwards data packets along a network.

Q2. What is a ‘protocol’ in networking?
Ans. A protocol is a set of invisible computer rules that enable two devices to connect and transmit data to one another.

Q3. Differentiate between a switch and a hub?
Ans. Switches are used at the data link layer, while hubs are used at the physical layer.

Q4. How many layers are there in an OSI reference model? Name them.
Ans. There are 7 layers in an OSI (Open Systems Interconnection) reference model. They are:
Physical layer
Data link layer
Network layer
Transport layer
Session layer
Presentation layer
Application layer

Q5. What is the difference between a ‘broadcast domain’ and a ‘collision domain’?
Ans. A broadcast domain is a logical division of a computer network, in which all nodes can reach other by broadcast at the data link layer.

A collision domain is a section of a network where data packets can collide with one another when being sent on a shared medium or through repeaters.

Q6. What is the size of an IP address?
Ans. 32 it for IPv4 and 128 bit for IPv6.

Q7. What is a DLCI?
Ans. DLCI (Data Link Connection Identifiers) are used to uniquely identify each virtual circuit that exists on the network.

Q8. Name the different types of networks
Ans. There are two different types of networks – 1) peer-to-peer and 2) server-based

Q9. What is the difference between a ‘half-duplex’ and a ‘full-duplex’ system?
Ans. In a half-duplex system, communication takes place in only one direction, while in a full-duplex system, communication takes place in both directions.

Q10. What is PoE (Power over Ethernet)?
Ans. Power over Ethernet (PoE) refers to the technology which allows electric power along with data on Ethernet cabling.

Q11. What is the use of ‘ping’ command?
Ans. Ping (Packet Internet Groper) is a computer network tool that is used to test whether a particular host is reachable across an IP network.

Q12. What is ‘round-trip time’?
Ans. Round-trip time, or round-trip delay, is the time required for a packet to travel from a specific source to a specific destination and back again.

Q13. What is the difference between public and private IP?
Ans. Public IP is used across the internet, while private IP is used within the local LAN.

Q14. What is the difference between ‘cross cable’ and ‘straight cable’?
Ans. Cross cables are used to connect same group devices while straight cables are used to connect different group devices.

Q15. At which layer of OSI does frame relay technology work?.
Ans. At data link layer.

Q16. What is the size of a Cisco ping packet?
Ans. The size of a Ping packet in Cisco by default is 100 bytes.

Q17. How many VTP modes are in a switch? Name them.
Ans. There are three types of VTP modes. They are – server, client and transparent.

Q18. What is the difference between static and dynamic IP addressing?
Ans. Dynamic IP addresses can change every time a device connects to the internet. Static IP addresses are reserved and do not change with time.

Q19. What is ‘subnet’? Why is it used?
Ans. Subnets are used in IP network to optimise the performance of a network because it reduces traffic by breaking a large network into smaller networks.

Q20. What does MTU stand for? What is the default size?
Ans. MTU stand for maximum transmission unit. The default MTU size is 1500 bytes.