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As we all know Update is always required for a better Knowledge, here are some important & quick Interview Question Update for the Networking Domain Students.


What is HSRP?

HSRP, or the Hot Stand by Routing Protocol, is a Cisco proprietary protocol that brings routing functionality to end devices that would otherwise not be capable of taking advantage of redundant network connections. HSRP enables a pair of Cisco routers to work together to present the appearance of a single virtual default-gateway to end devices on a LAN segment.

What is the difference between a Public IP address and a Private IP address?

Public address space is a unique address that is assigned to a company. Private address space is not recognized by the Internet and can be used by anyone within their private network.

What does AAA stand for?

Authentication, authorization, and accounting

 The H.323 protocol is used for what?

H.323 is used for multi service (multimedia) applications, usually in a Voice over IP environment.

 What type of routing protocol maintains neighbours?

Link State

What is the range of values for administrative distance?


 Describe the difference between uni cast, multi cast, and broadcast traffic?

Unicast traffic flows from a single source to a single destination MAC address. Multicast traffic flows from a single source MAC address to many destinations and uses a functional MAC address. Broadcast traffic is from a single source to all devices on the Ethernet segment. This is specified by a destination MAC address of all ones.

What are the four different Ethernet encapsulation types?

From the Cisco IPX encapsulation command they are ARPA, NOVEL-ETHER, SAP and SNAP

What are the three main tasks of a transparent bridge?

Learning, Forwarding, Filtering

 What type of routing protocol is EIGRP?


While troubleshooting a connectivity problem on the network, you issue the ping command from your PC command prompt, but the output shows “request times out.” At which OSI layer is this problem associated with?

The Network Layer

What algorithm does OSPF use to compute its route table?

OSPF uses the shortest path first (SPF) algorithm, which is also known as the Dijkstra algorithm.

 What is a stub area?

A stub area is an area that does not accept routing updates from outside its autonomous system.

What does the TTL field of an IP packet header do?

The TTL field indicates the maximum time that a packet can be on the network. Each router that processes this packet decrements the TTL value by 1. If the value reaches zero, the packet is discarded from the network. The purpose of this field is to eliminate the possibility of a packet endlessly traversing the network.

What is the primary purpose of a LAN?

The primary purpose of a local-area network is to allow resource sharing. The resources may be devices, applications, or information. Examples of shared resources are files, databases, e-mail, modems, and printers.

What is a protocol?

A protocol is an agreed-upon set of rules. In data communications, the rules usually govern a procedure or a format.

What is the purpose of a MAC protocol?

A Media Access Control protocol defines how a given LAN medium is shared, how LAN devices connected to the medium are identified, and how frames transmitted onto the medium are

What is a frame?

A frame is a digital “envelope” that provides the information necessary for the delivery of data across a data link. Typical components of a frame are identifiers (addresses) of the source and destination devices on the data link, an indicator of the type of data enclosed in the frame, anderor-checking information.

What feature is common to all frame types?

A feature common to all frame types is a format for identifying devices on the data link.

What is a MAC address or MAC identifier?

A Media Access Control address or identifier is a means by which individual devices connected to a data link are uniquely identified for the purpose of delivering data.

Why is a MAC address not a true address?

An address specifies a location. A MAC address is not a true address because it is permanently associated with the interface of a specific device and moves whenever the device moves. A MAC identifies the device, not the location of the device.

What are the three sources of signal degradation on a data link?

The three sources of signal degradation on a data link are attenuation, interference, and distortion. Attenuation is a function of the resistance of the medium. Interference is a function of noise entering the medium. Distortion is a function of the reactive characteristics of the medium, which react differently to different frequency components of the signal.

What is the purpose of a repeater?

A repeater is a device that extends the useful range of a physical medium by reading a degraded signal and producing a “clean” copy of the signal.

What is the purpose of a bridge?

A bridge is a device that increases the capacity of a LAN. A bridge divides the data link into segments, forwarding only traffic that is generated on one segment and is destined for another segment. By controlling and limiting the traffic on a data link, more devices may be attached to the LAN.

What makes a transparent bridge transparent?

A transparent bridge “listens promiscuously” on each of its ports. That is, it examines all frames on all media to which it is attached. It records the source MAC identifiers of the frames, and the ports on which it learns the identifiers, in a bridging table. It can then refer to the table when deciding whether to filter or forward a frame. The bridge is transparent because it performs this learning function independently of the devices that originate the frames. The end devices themselves have no knowledge of the bridge.

Name three fundamental differences between LANs and WANs?

Three fundamental differences between local-area and wide-area networks are:

LANs are limited to a small geographic area, such as a single building or small campus.

WANs cover a large geographic area, from citywide to worldwide.

LANs usually consist entirely of privately owned components. Some components of a WAN, such as a packet switching network or point-to-point serial links, are usually leased from a service provider.

A LAN provides high bandwidth at a relatively cheap price. The bandwidth across a WAN is significantly more expensive.

What is the purpose of a broadcast MAC identifier? What is the broadcast MAC identifier, in hex and in binary?

A broadcast MAC identifier, when used as the destination address of a frame, signifies that the data is for all devices attached to the data link. In binary, the broadcast MAC identifier is all ones. In hex, it is ffff.ffff.ffff.

What is the primary similarity between a bridge and a router? What is the primary difference between a bridge and a router?

The primary similarity between a bridge and a router is that both devices increase the number of hosts that may be interconnected into a common communications network. The difference is that a bridge works by interconnecting separate segments of a single network, whereas a router interconnects separate networks.

What is a packet? What is the primary similarity between a frame and a packet? What is the primary difference between a frame and a packet?

A packet is the means by which data is transported from one network to another. The similarity between a frame and a packet is that they both encapsulate data and provide an addressing scheme for delivering the data. The difference between a frame and a packet is that the frame delivers data between two devices sharing a common data link, whereas a packet delivers data across a logical pathway, or route, spanning multiple data links.

As a packet progresses across an inter network, does the source address change?

Neither the source nor the destination address of a packet changes as it progresses from the source of the packet to the destination.

What is a network address? What is the purpose of each part of a network address?

Network addresses are the addresses used in packets. Each network address has a network part, which identifies a particular data link, and a host or node part, which identifies a specific device on the data link identified by the network part.

What is the primary difference between a network address and a data link identifier?

A packet identifies a device from the perspective of the entire internetwork. A frame identifies a device from the perspective of a single data link. Because the connection between two devices across an internetwork is a logical path, a network address is a logical address. Because the connection between two devices across a data link is a physical path, a data link identifier is a physical address.

What are the five layers of the TCP/IP protocol suite? What is the purpose of each layer?

The five layers of the TCP/IP protocol suite are the following:

-Physical layer

-Data link layer

-Internet (or IP) layer

-Host-to-host layer

-Application layer

What is the most common IP version presently in use?

The most common IP version now in use is version 4.

What is fragmentation? What fields of the IP header are used for fragmentation?

Routers perform fragmentation when a packet is longer than the maximum packet length (Maximum Transmission Unit, or MTU) supported by a data link onto which the packet must be transmitted. The data within the packet will be broken into fragments, and each fragment will be encapsulated in its own packet. The receiver uses the Identifier and Fragment Offset fields and the MF bit of the Flags field to reassemble the fragments.

What is the purpose of the TTL field in the IP header? How does the TTL process work?

The Time to Live (TTL) field prevents “lost” packets from being passed endlessly through the IP internetwork. The field contains an 8-bit integer that is set by the originator of the packet. Each router through which the packet passes will decrement the integer by one. If a router decrements the TTL to zero, it will discard the packet and send an ICMP “time exceeded” error message to the packet’s source address.