Apart from getting jobs in networking, CCNA Certification will help you in mastering routing protocols like RIP, EIGRP and OSPF. The most important fact is that, the certification program is not restricted to a particular stream. All students and working professionals from various backgrounds like B.E, B.Tech, B.Sc, MCA, and diploma can undergo training for CCNA and look for a career in networking.


1) What are the two types of IP addresses available?

There are two types, namely IPv4 and IPv6

IPv4- 32 bit address and IPv6-128 bit address.

2) Which IP address is used for loopback address and for what purpose? is used for loopback address and also for local testing purposes.

Loopback means looping to our own systems, checking our own systems. It is used to test whether TCP/IP stack is correctly installed.

3) What do you mean by OSI layers?

Open System Interconnection (OSI)layers.

  • It is a set of rules used to describe how to make networks.
  • Whenever we design new network or hardware device, we have to follow OSI reference model.
  • There are seven layers, which means seven set of rules; they are designed by ISO (international standard organization).
  • It tells what are the services/ports/applications used.

4) What are the major functions of transport layer?

  • Segment fragmentation
  • Numbering segmenting
  • Reliable and unreliable data delivery
  • Error detection & error correction
  • Flow control
  • Multi tasking
  • Windowing

5) What is data encapsulation and data de-encapsulation?

  • When data is sent from a higher layer to a lower layer, each layer adds some information to the original data; this is called as encapsulation. The information added is called as header.
  • When data is sent from lower layer to higher layer, each layer will remove information from the other layer. This is called as de-encapsulation.

6) What are the major functions of routers?

  1. A) Packet switching- all incoming data is switched to packets. It deals only with packets (data with IP address)
  2. B) Packet filtering- router sends and receives only packets. It is used in WAN, so all incoming packets are filtered mainly for security.
  3. C) Internetwork communication- joining of two or more networks.
  4. D) Path selection- router is used to select the shortest and best path from source to destination.
  5. E) QoS- Quality of Service: QoS is the ability of the n/w to provide better or special service to a set of users or applications.

7) What is the main purpose of DHCP?

  • DHCP is dynamic host configuration protocol.
  • DHCP allows devices to acquire their addressing information dynamically.
  • DHCP is actually based on bootstrap protocol (bootp).
  • It is built on a client/server model and defines two components.
  1. Server- delivering host configuration information
  2. Client- requesting and acquiring host configuration information

8) What are the two types of cables available?

  • Straight through cable
  • Crossover cable

9) Which registry key is used in normal mode of router and what registry key is used to recover password?

  • The registry key used in normal mode is 0x2102  to 0x210f.
  • To recover password we have to use the registry key 0x2142.

10) Define CDP and its functions?

  • CDP is Cisco discovery protocol
  • It is a layer 2 protocol
  • It works based on mac addresses.(h/w addresses)
  • It is used to find adjacent Cisco devices.
  • It is a Cisco proprietary protocol means used to find only the neighbouring Cisco devices.

It is used to find out

  1. IP addresses
  2. Port numbers
  3. iOS details
  4. Router models
  5. Switch models
  6. Interface details
  7. Device ID- hostname

11) What are the two types of routes available in routers?

  1. A) Static or Static default

Static, if one route is fixed for transmission it will stay fixed. If that link is down it cannot connect and reach the destination even if there are alternate paths. Static route is used for smaller networks. Symbol of static is s.
Static default– it sends data to unknown destination + specified n/w.ex in isp we can have different connections. It uses as the address for connection. Symbol of static default is s*.

  1. B) Dynamic route

It will choose the path by itself. Paths are found by the routing protocols.
Chooses the best or main path. If that path fails, it will find out the next alternate path. Routing protocols like RIP/EIGRP/OSPF decide the paths.

12) What is distance vector? Explain with example.

Distance Vector Protocols send periodic updates every 30 secs or at some time interval to the adjacent routers.In case if there is a link failure immediately,they inform to update only after 30 secs. For example, RIP routing information protocol is a distance vector protocol. Here distance indicates length between two routers and vector means in which link direction the link is connected between them.

13) What is the administrative distance of RIP, EIGRP and OSPF?

The administrative distance for:

  • RIP: 120.
  • EIGRP: 90
  • OSPF: 110

14) What is switching?

Switching is the process of using the hardware address/mac address of devices on a LAN to segment a n/w. Switches break up large collision domains into smaller ones and that a collision domain is a n/w segment with two or more devices sharing the same bandwidth.

Switch is a layer device and deals with frames (data with mac address).

15) What is meant by VLAN and what is its purpose?

A VLAN is a logical and orderly alignment of network users and resources. These are connected to ports on a switch which are administratively defined.

It is used to segment big networks and connect with routers for security purposes.

For joining two different networks or virtual VLANs, we need routers.

16) What happens if there is no VLAN in switch ports?

If there is no VLAN in switches, it can lead to a broadcast storm; as all ports will start broadcasting. By default all ports in switches are in VLAN1 and they can send and receive data within VLAN1. We can also create multiple VLANs and join them using routers.

17) What are the two ports of switches?

  1. Access port
  2. Trunk port
  • An Access port belongs to and carries the traffic of only one VLAN. We can pass only single VLAN information. It is used to connect switch ports with computers with minimum speed of 10Mbps.
  • A Trunk port is used for multiple connections between switch to routers and switch to switch.

Switch to router- minimum speed:100mbps. It is used for inter VLAN communications, when connected with the router.

18) What is VTP?

VTP is VLAN trunking protocol. It is used to allow VLAN information to be automatically propagated throughout the switching environment.

19) What are the various of modes in VTP?

There are three modes in VTP :

  • Server mode
  • Client mode
  • Transparent mode

Default mode is server.

  • Server mode– Full control over VLAN creations and modifications for their domains.
  • Client mode– VTP clients do not allow the administrator to create, change or delete any VLAN’s; instead they listen to the VTP’s advertisements from other switches and modify their VLAN configuration accordingly.
  • Transparent mode– VTP transparent mode switches will not participate in VTP advertisements. It can create and delete VLAN’s that are local only to itself. It will not propagate to other switches, and will not advertise its own VLAN configuration.

20) Define STP. Why is it used?

STP (Spanning Tree Protocol) was created by digital equipment corporation. The new version was created by IEEE which is 802.1d. STP is a bridge-to-bridge protocol used to maintain a loop free n/w. Redundant links between switches are a good idea because they help prevent complete network failures in the event one link stops working.

21) How many bits are available in IPv6?

  • IPv6 contains 128 bits with 8 groups. It has n/w part and host part. Each group has 16 bits.
  • So 8*16=128, it is in hexadecimal format (00ff). There are 32 hexadecimal numbers.
  • Each groups (4 hex digits) are separated by colon.