CCNA Interview Questions and Answers

 CCNA Interview Questions and Answers 

Question 1 – Tell us something about OSI Model ?

❑ OSI stands for Open Systems Interconnection.

❑ It has been developed by ISO – ‘International Organization of Standardization‘, in the year 1984.

❑ It is a reference model and have  7 layer architecture with each layer having specific functionality to perform.

 

Question 2 – What are the 7 layers in OSI Model ? 

❑ Layer 1 - Physical Layer       

❑ Layer 2 - Data Link Layer 

❑ Layer 3 - Network Layer

❑ Layer 4 - Transport Layer 

❑ Layer 5 - Session Layer

❑ Layer 6 - Presentation Layer

❑ Layer 7 - Application Layer ❑Please Do Not Tell Sales People Anything

Question 3 –What is a IP Address?

❑Internet Protocol (IP Address) is a 32-bits to 128-bits identifier for a device on TCP/IP protocol. 

❑IP address of a device must be uniquely defined for communication. 

❑And it has two versions which are IPv4 (32-bits) and IPv6 (128-bits).

 

Question 4 – What are the difference between a hub, switch and a router ?

❑ A hub is a basic networking device that connects multiple devices in a LAN but operates at the physical layer (Layer 1).

❑ A switch is a more intelligent device that operates at the data link layer (Layer 2) and uses MAC addresses to forward frames to the appropriate ports.

❑ A router operates at the network layer (Layer 3) and connects different networks, making forwarding decisions based on IP addresses.

 

Question 5 – What is a RJ45 ?

❑RJ45 is the type of the connector used for Ethernet cables.

 

 

Question 6 – By using which command you can trace an IP address 10.1.1.1 on a Router ?

❑traceroute 10.1.1.1 

Question 7 –What is Routing and types of Routing ?

❑ Routing is a process of forwarding packets from one network to another network by selecting best path  & which is performed by a layer 3 i.e network layer devices.

❑ Types of Routing 

❑ 1) Default Routing 

❑ 2) Static Routing 

❑ 3) Dynamic Routing 

Question 8 – What is PING used for?

❑PING is packet Internet groper. 

❑It is used to test the Layer 3 i.e Network Layer reachability of a host on a network. 

 

 

Question 9 – What is the AD Value ?

❑ Administrative Distance AD Value defines the trustworthiness of a routing protocol. 

❑ i.e How reliable the route/s of the routing protocol are !  

❑ Range - <0 - 255>  

Question 10 – What is  AD Value of OSPF?

❑ 110 

AD Values 

❑ Connected interface - 0 

❑ Static route  - 1

❑ External BGP - 20 

❑ EIGRP - 90 

❑ OSPF - 110

❑ RIP - 120 

❑ Internal BGP - 200 

❑ Unknown - 255 (This route is not used)

 

Question 11 – What is the purpose of creating VLANS ?

❑ Broadcast control is the main purpose of creating vlans Other purpose of creating VLANs

❑ VLANs provides Network Security

❑ VLANs provides Segmention

❑ VLANs provides Flexibility - a user can easily move across the physical location and still remain in the same vlan

Question 12 – What is meant by Inter-Vlan Routing ?

❑ VLAN divides the broadcast domains so the hosts can communicate with the other hosts in the same vlan.

❑ When the hosts from one vlans wants to communicate with hosts in other vlan the traffic must be routed between them.

❑ This is known as Inter-Vlan Routing

❑ Inter-Vlan Routing can be achieve either by creating SVI or using Router-on Stick.

 

Question 13 – What is an Autonomous System ?

❑ An Autonomous System (AS) is a group of networks under a single administrative control.

❑ An AS can be Internet Service Provider (ISP) or a large Enterprise Organization.

❑ Each AS will have an ASN

❑ Autonomous System Number (ASN) - 16 bit binary number & we can represent (2^16) numbers, which is equal to 65536 in decimals.

❑ Range of ASN – 0 to 65535

❑ 0 , 65535 - Reserved

❑ 1 – 64511 - Internet Routing – ISP AS

❑ 64512 – 65534 Private Use - Private AS

Question 14 – What is the difference between TCP and UDP?

❑ TCP (Transmission Control Protocol) is a connection-oriented protocol that ensures reliable and ordered delivery of data.

❑ UDP (User Datagram Protocol) is a connectionless protocol that does not guarantee reliable delivery but offers faster transmission. 

❑ TCP is used for applications that require reliable data delivery, while UDP is suitable for real-time applications like streaming and gaming.

Question 15 – What is the purpose of ACLs (Access Control Lists) in networking?

❑ ACLs are used to control and filter traffic based on specified criteria, such as source or destination IP addresses, ports, or protocols.

 

Question 16 – Explain the concept of latency in networking  ?

❑ Latency is the time delay between the transmission of data from the source and its reception at the destination. 

Question 17 – What is ARP?

❑ Address Resolution Protocol (ARP) is a network protocol, which is used to map a network layer protocol address (IP Address) to a data link layer hardware address (MAC Address). 

❑ ARP basically resolves IP address to the corresponding MAC address.  

Question 18 – What is the metric in EIGRP?

❑ Composite Metric.

❑ It don’t consider single criteria to calculate the metric but uses number of criteria which includes Bandwidth , Load , Delay ,Reliability and MTU.

❑ The weightage of these criteria's is defined by something know as K values i.e. Metric Weight. 

❑ By default K values for Bandwidth and Delay are 1 . 

❑ Hence while calculating the metric only Bandwidth and Delay are considered.

Question 19 – What is the metric in OSPF?

❑ Metric is Cost.

❑ Cost depends upon Bandwidth of the link .

❑ Cost is Inversely proportional to the Bandwidth.

❑ Means Greater the Bandwidth less the cost and better the path.

❑ Cost = 100 / Bandwidth (in Mbps)

Question 20 – What is MTU (Maximum Transmission Unit) in a router ?

❑ The maximum transmission unit (MTU) of an interface tells router the largest IP packet that can be forwarded out on that interface. 

Question 21 – What is BGP?

❑Border Gateway Protocol is an Exterior Gateway Routing Protocol which runs between two or more Automous system.

❑ BGP is also known as Routing Protocol of Internet.

 

Question 22 –What is the role of a firewall in networking?

❑ A firewall is a network security device that monitors and controls incoming and outgoing network traffic based on predetermined security rules. It acts as a barrier between a secure internal network and untrusted external networks.

 

Question 23– What is the purpose of DNS?

❑ DNS (Domain Name System) translates domain names into IP addresses, allowing users to access websites using human readable names instead of numerical IP addresses.

 

Question 24 – What are the port numbers used by Telnet and SSH?

❑ Telnet – 23

❑ SSH - 22

 

 

 

Best of Luck !!!!

 

NES