CCNA Interview Questions | CCNA Interview Questions and answers pdf

 

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.

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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.

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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.

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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.

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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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