CCNA
Interview Questions
A list of top frequently asked CCNA
interview questions and
answers are given below.
1) What is Routing?
- Routing is a process of finding a path to transfer
data from source to destination.
- Routing can be performed in a variety of networks
such as circuit switched networks and computer networks.
- In packet switching networks, routing makes a
decision that directs the packets from source to the destination.
- Routing makes use of a routing table, which
maintains the routes of various destinations.
Types of routing:
Static
routing:
1.
Static routing : Static
routing is a routing technique where an administrator manually adds the routes
in a routing table. Static routes are used when the route selections are
limited. Static routes can also be used in those situations where the devices
are fewer and no need to change in the route configuration in future.
2.
Dynamic routing:
Dynamic routing is a routing technique where protocols automatically update the
information of a routing table.
2) What is the difference
between switch and hub?
|
Basis
of Comparison |
Hub |
Switch |
|
Description |
Hub is a networking
device that connects the multiple devices to a single network. |
A switch is a control
unit that turns the flow of electricity on or off in a circuit. |
|
Layer |
Hubs are used at the
physical layer. |
Switches are used at the
data link layer. |
|
Transmission type |
Transmission type can be
unicast, broadcast or multicast. |
Initially, the transmission
type is broadcast and then is unicast. |
|
Ports |
Hub has 4/12 ports. |
The switch has 24/48
ports. |
|
Transmission mode |
Half duplex |
Half/Full duplex. |
|
Collisions |
Collisions occur commonly
in a Hub. |
No collisions occur in a
full duplex switch. |
|
Address used for data
transmission |
Hub uses MAC address for
data transmission. |
The switch uses a MAC
address for data transmission. |
|
Data transmission form |
Electrical signal is a
data transmission form of a hub. |
A Frame is a data
transmission form of a switch. |
3) What is the difference
between Switch and Router?
|
Basis of Comparison |
Router |
Switch |
|
Description |
It is a layer 3 device
that connects the two different networks and identifies the network devices
based on their IP addresses. |
It is a layer 2 device
and determines the network devices based on their MAC addresses. |
|
Mode of transmission |
Router transmits the data
in the form of packets. |
Switch transmits the data
in the form of frames. |
|
Address used |
It uses an IP address for
the data transmission. |
It uses a MAC address to
transmit the data. |
|
Layer of OSI model |
It uses Layer 3 OSI model
and layer is the network layer. |
It uses layer 2 OSI model
and layer is the data link layer. |
|
Table |
It uses a routing table
for routes to move to the destination IP. |
It uses a Content address
memory table for MAC addresses. |
|
Network used |
It is used for WAN and
LAN networks. |
It is used only for LAN
networks. |
|
Mode of transmission |
Router is used in a
full-duplex mode. |
A switch is used in half
as well as in a full-duplex mode. |
4) What are the
advantages of using Switches?
Advantages of using
Switches:
- Switches are used to receive a signal and create a
frame out of the bits from that signal. The signals enable you to get
access and read the destination address and after reading that it forward
that frame to appropriate frame. So, switches are the significant part of
the transmission.
5) What are Routers?
- The devices known as Routers do the process of
routing. Routers are the network layer devices.
- The router is a networking device which is used to
transfer the data across the networks, and that can be wired or wireless.
- Routers use headers and routing table to determine
the best route for forwarding the packets.
- Router analyzes the data which is being sent over
the network, changes how it is packaged and send it over the network.
Examples of routers are:
1.
Brouter:
Brouter stands for "Bridge Router". It serves both as a router and
bridge.
2.
Core router:
Core router is a router in the computer network that routes the data within a
network, but not between the networks.
3.
Edge router: An
edge router is a router that resides at the boundary of a network.
4.
Virtual router: A
virtual router is a software-based router. The virtual router performs the
packet routing functionality through a software application. A Virtual Router
Redundancy protocol implements the virtual router to increase the reliability
of the network.
5.
Wireless router: A
wireless router is a router that connects the local networks with another local
network.
6) What is the advantage
of VLAN?
VLAN is a custom network which is created
from one or more existing LAN's. VLAN facilitates you to create a collision
domain by groups other than just physical location while in conventional LAN
domains are always tied to physical location.
Advantage
of VLAN:
- Broadcast control: A VLAN (Virtual Area Network) removes the physical
layer and, it logically separates the networks within networks creating a
smaller broadcast domain. It reduces the size of the broadcast domain,
therefore, improving the efficiency of the network.
- Simplified administration: When a computer is moved to
another location, but it stays on the same VLAN without any hardware
configuration.
- Security:
- LAN segmentation: Virtual Area Networks are used to
logically separate layer 2 switch networks. Users on different VLAN cannot
communicate with each other. Therefore, it's a great way of segmentation
and provides security.
- Dynamic VLANs: The Dynamic VLAN's are created
using the software. The VLAN Management Policy Server (VMPS) is an
administrator that dynamically allocates the switch ports based on the
information available such as the MAC addresses of the device.
- Protocol-based VLANs: The switch that depends on the protocol
based VLANs, then the traffic will be segregated by a particular protocol.
7)
What is HDLC?
- HDLC stands for High-Level Data
Link Control protocol. It is the property protocol of Cisco which is the
default encapsulation operated with Cisco routers.
- HDLC adds the information in a
data frame that allows the devices to control the data flow.
- HDLC is a bit-oriented protocol
that supports both half and full duplex communication.
- HDLC offers flexibility, adaptability,
reliability, and efficiency of operation for synchronous data
communication.
- It supports both point-to-point
and point-to-multipoint communication.
- It supports synchronous as well as
asynchronous communication.
- It provides full data
transparency, i.e., the output delivered has the same bit sequence as the
input without any restriction.
8) What are the
advantages of LAN switching?
LAN switching: LAN switching enables the
multiple users to communicate with each other directly. LAN switching provides
the collision-free network and high-speed networking.
Following are the main
advantages of LAN switching:
- Increased network scalability:
LAN switching can handle the increasing
amount of work. Therefore, we can say that when the business grows, the network
can expand easily.
- Improved bandwidth performance:
We require higher bandwidth performance when
users operate multimedia applications or some database interactions.
- Multiple simultaneous connections:
LAN switching allows multiple simultaneous connections,
i.e., it can transfer the multiple data at the same time. This cannot be
possible in the case of a hub-based network.
- Reduced congestion and transmission delay:
LAN switching improves the performance of a
network as a segmented network consists of fewer hosts per subnetwork and thus,
minimizing the local traffic.
- No single point of failure:
LAN switching provides the proper network
designing. Therefore, there are fewer chances of network failure.
- Allows full duplex data transmission: LAN switching allows full duplex
data transmission, i.e., the data can be transferred in a bidirectional
line at the same time.
9) What is DLCI?
DLCI stands for Data
Link Connection Identifiers. These are normally assigned by a frame relay service
provider to identify each virtual circuit that exists on the network uniquely.
10) What are the
different types of networks?
These are the two major types of networks:
1. Peer-to-Peer Network:
- In a
peer-to-peer network, 'peers' are the computers which are connected to
each other through an internet connection.
- The
computer systems on the network without the need for any computer server.
- Therefore,
the computer in P2P is a "computer server" as well as a
"client".
- Requirements
for a computer to have a peer-to-peer network are the internet connection
and P2P software.
- Some of
the common P2P software peers include Kazaa, Limewire, BearShare,
Morpheus, and Acquisition.
- Once we
are connected to the P2P network, then we able to search the files on
other people's computer.
Types of a peer-to-peer
network:
1. Pure
P2P:
In P2P, peers act as a client and server. There is no central server and
central router present in the pure P2P.
2. Hybrid
P2P:
Hybrid P2P has a central server that stores the information and responds to the
request for that information. Peers are used for hosting the information as a
central server does not store the files. Nasper is an example of Hybrid P2P.
3. Mixed
P2P:
Mixed P2P is a combination of pure P2P and Hybrid P2P.
2. Server-based Network
- In a server-based
network, server act as a base for the network known as a central server.
- The
central server handles multiple tasks such as authenticating users,
storing files, managing printers, and running applications such as
database and email programs.
- In case of
a server-based network, security is centralized in the system which allows
the user to have one login id and password to log on to any computer
system.
- Server-based
networks are more complex and costly and often requires full- time
services for administration.
- In
server-based networks, the majority of traffic occurs between the servers.
11) What is the
difference between cross cable and straight cable?
o
Cross
cables are used to connect the same group devices while straight cables are
used to connect different group devices.
o
For example: If you want to connect one PC to another
PC, you have to use cross cable while, to connect one switch to a router, you
have to use a straight cable.
12) What is the
difference between private IP and public IP?
Following are the
differences between public IP address and private IP address:
|
Basis
of Comparison |
Public
IP address |
Private
IP address |
|
Definition |
It is used for the
identification of a home network to the outside world. |
It is used for the
identification of a network device within the home network. |
|
Uniqueness |
Public IP address is
unique throughout the network. |
Private IP address can be
the same of two different networks assigned to different computers. |
|
Example |
202.60.23.1 |
192.168.0.3 |
|
Usage |
It is used over the
internet or other WAN. |
This type of address can
be used on a local area network or for the computers that are not connected
to the internet. |
|
Communication |
Public IP address is
routable. Therefore, communication among different users is possible. |
Private IP address is not
routable. Thus, communication among different users is not possible. |
13) What is the
difference among straight cable, cross cable and rollover cable?
Straight cable:
- Straight
cable is used to connect different group devices. For example Switch-
Router.
- Straight
cable is a kind of twisted pair cable used in a local area network to
connect a computer to a network hub such as a router.
- Straight
cables are used for linking different devices.
- It is an 8
wired patch cable.
- It is also
used for connecting PC to the switch or router to a hub.
- The main
purpose of a straight cable is to connect a host to the client.
Cross cable:
- Cross cable is used to connect the same group
devices. For example Switch-Switch.
- Cross cable is a cable used to interconnect two
computers by reversing their respective pin contacts.
- Cross cable is a cross-wired cable used to connect
the two computers or hosts directly.
- Cross cable is used when two similar devices are to
be connected.
- Cross cable crisscross each other, and this makes
the communication of two devices at the same time.
Rollover cable:
- Rollover cable is used to connect the console port
to the computer.
- Rollover cable is used to connect the computer's
terminal to the network's router console port.
- Rollover cable is referred to as a Cisco console
cable, and it is flat and light blue in color.
- Another name of a rollover cable is Yost cable.
- Rollover cable is identified by comparing the end of
the cable with another cable as rollover cables are beside each other.
- Rollover cable allows the programmer to
connect to the network device and can manipulate the programming whenever
required.
14) What is the
difference between tracert and traceroute?
Differences between tracert and traceroute
|
Basis
of Comparison |
tracert |
traceroute |
|
Description |
The tracert command is a
command prompt command used to show the route that the packet takes to move
from the source to the destination whatever we specify. |
The traceroute command is
a command used to show the route from your computer to the destination that
you specify. |
|
Device used |
The tracert command is
used on pc. |
The traceroute command is
used on a router or switch. |
|
Operating system |
The tracert command is
used in Windows NT based OS. |
The traceroute command is
used in UNIX OS. |
15) Explain the terms
Unicast Multicast, Broadcast.
Unicast:
- It specifies one to one communication.
- It is a communication technique in which data
communication takes place between two devices present in the network.
- Consider an example of browsing the internet. When
we sent a request for some page to the web server, then the request
directly goes to the web server to locate the address of a requested page.
Therefore, this is one to one communication between client and server.
- Downloading the files from the FTP server is also
the best example of unicast communication.
Multicast:
- It specifies one to group communication.
- It is a communication technique in which data
communication takes place between a group of devices.
- Multicast uses IGMP(Internet Group Management
Protocol) protocol to identify the group.
- Consider an example of video conferencing. If any
user in a particular group can initiate the call and the people belongs to
this group can participate in this call.
- Sending e-mail to a particular mailing group can
also be considered as the example of multicast communication.
Broadcast:
- It specifies one to all communication.
- It is a communication technique in which data
communication takes place among all the devices available in the network.
- Broadcasting can be achieved in two ways:
1. By using a high-level
standard, i.e., Message passing interface. It is an interface used for
exchanging the messages between multiple computers.
2. By using a low-level
standard, i.e., broadcasting through an ethernet.
- Network is not secure in broadcasting as it can lead
to a data loss if intruders attack the network.
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