NETWORKING Interview Question ANSWERS 3

NETWORKING Interview Question ANSWERS 3

81. What is Beaconing?

The process that allows a network to self-repair networks problems. The stations on the network notify the other stations on the ring when they are not receiving the transmissions. Beaconing is used

in Token ring and FDDI networks.

82. What is redirector?

Redirector is software that intercepts file or prints I/O requests and translates them into network requests. This comes under presentation layer.

83. What is NETBIOS and NETBEUI?

NETBIOS is a programming interface that allows I/O requests to be sent to and received from a remote computer and it hides the networking hardware from applications.

NETBEUI is NetBIOS extended user interface. A transport protocol designed by microsoft and IBM for the use on small subnets.

84. What is RAID?

A method for providing fault tolerance by using multiple hard disk drives.

85. What is passive topology?

When the computers on the network simply listen and receive the signal, they are referred to as passive because they don't amplify the signal in any way. Example for passive topology -linear bus.

86. What is Brouter?

Hybrid devices that combine the features of both bridges and routers.

87. What is cladding?

A layer of a glass surrounding the center fiber of glass inside a fiber-optic cable.

88. What is point-to-point protocol?

A communications protocol used to connect computers to remote networking services including Internet service providers.

89. How Gateway is different from Routers?

A gateway operates at the upper levels of the OSI model and translates information between two completely different network architectures or data formats.

90. What is attenuation?

The degeneration of a signal over distance on a network cable is called attenuation.

91. What is MAC address?

The address for a device as it is identified at the Media Access Control (MAC) layer in the network

architecture. MAC address is usually stored in ROM on the network adapter card and is unique.

92. Difference between bit rate and baud rate.

Bit rate is the number of bits transmitted during one second whereas baud rate refers to the number

of signal units per second that are required to represent those bits.

baud rate = (bit rate / N)

where N is no-of-bits represented by each signal shift.

93. What is Bandwidth?

Every line has an upper limit and a lower limit on the frequency of signals it can carry. This limited

range is called the bandwidth.

94. What are the types of Transmission media?

Signals are usually transmitted over some transmission media that are broadly classified in to two

categories.

a.) Guided Media: These are those that provide a conduit from one device to another that include

twisted-pair, coaxial cable and fiber-optic cable. A signal traveling along any of these media is directed

and is contained by the physical limits of the medium. Twisted-pair and coaxial cable use metallic that

accept and transport signals in the form of electrical current. Optical fiber is a glass or plastic cable

that accepts and transports signals in the form of light.

b.) Unguided Media: This is the wireless media that transport electromagnetic waves without using a

physical conductor. Signals are broadcast either through air. This is done through radio

communication, satellite communication and cellular telephony.

95. What is Project 802?

It is a project started by IEEE to set standards to enable intercommunication between equipment from

a variety of manufacturers. It is a way for specifying functions of the physical layer, the data link layer

and to some extent the network layer to allow for interconnectivity of major LAN protocols.

It consists of the following:

1. 802.1 is an internetworking standard for compatibility of different LANs and MANs across

protocols.

2. 802.2 Logical link control (LLC) is the upper sublayer of the data link layer which is nonarchitecture-

specific, that is remains the same for all IEEE-defined LANs.

3. Media access control (MAC) is the lower sublayer of the data link layer that contains some

distinct modules each carrying proprietary information specific to the LAN product being used.

The modules are Ethernet LAN (802.3), Token ring LAN (802.4), Token bus LAN (802.5).

4. 802.6 is distributed queue dual bus (DQDB) designed to be used in MANs.

96. What is Protocol Data Unit?

The data unit in the LLC level is called the protocol data unit (PDU). The PDU contains of four fields a

destination service access point (DSAP), a source service access point (SSAP), a control field and an

information field. DSAP, SSAP are addresses used by the LLC to identify the protocol stacks on the

receiving and sending machines that are generating and using the data. The control field specifies

whether the PDU frame is a information frame (I - frame) or a supervisory frame (S - frame) or a

unnumbered frame (U - frame).

97. What are the different type of networking / internetworking devices?

1. Repeater: Also called a regenerator, it is an electronic device that operates only at physical

layer. It receives the signal in the network before it becomes weak, regenerates the original

bit pattern and puts the refreshed copy back in to the link.

2. Bridges: These operate both in the physical and data link layers of LANs of same type. They

divide a larger network in to smaller segments. They contain logic that allow them to keep the

traffic for each segment separate and thus are repeaters that relay a frame only the side of

the segment containing the intended recipent and control congestion.

3. Routers: They relay packets among multiple interconnected networks (i.e. LANs of different

type). They operate in the physical, data link and network layers. They contain software that

enable them to determine which of the several possible paths is the best for a particular

transmission.

4. Gateways: They relay packets among networks that have different protocols (e.g. between a

LAN and a WAN). They accept a packet formatted for one protocol and convert it to a packet

formatted for another protocol before forwarding it. They operate in all seven layers of the OSI

model.

98. What is ICMP?

ICMP is Internet Control Message Protocol, a network layer protocol of the TCP/IP suite used by hosts

and gateways to send notification of datagram problems back to the sender. It uses the echo test /

reply to test whether a destination is reachable and responding. It also handles both control and error

messages.

99. What are the data units at different layers of the TCP / IP protocol suite?

The data unit created at the application layer is called a message, at the transport layer the data unit

created is called either a segment or an user datagram, at the network layer the data unit created is

called the datagram, at the data link layer the datagram is encapsulated in to a frame and finally

transmitted as signals along the transmission media.

100. What is difference between ARP and RARP?

The address resolution protocol (ARP) is used to associate the 32 bit IP address with the 48 bit

physical address, used by a host or a router to find the physical address of another host on its

network by sending a ARP query packet that includes the IP address of the receiver.

The reverse address resolution protocol (RARP) allows a host to discover its Internet address when it

knows only its physical address.

101. What is the minimum and maximum length of the header in the TCP segment and IP

datagram?

The header should have a minimum length of 20 bytes and can have a maximum length of 60 bytes.

102. What is the range of addresses in the classes of internet addresses?

Class A - 0.0.0.0 - 127.255.255.255

Class B - 128.0.0.0 - 191.255.255.255

Class C - 192.0.0.0 - 223.255.255.255

Class D - 224.0.0.0 - 239.255.255.255

Class E - 240.0.0.0 - 247.255.255.255

103. What is the difference between TFTP and FTP application layer protocols?

The Trivial File Transfer Protocol (TFTP) allows a local host to obtain files from a remote host but does

not provide reliability or security. It uses the fundamental packet delivery services offered by UDP.

The File Transfer Protocol (FTP) is the standard mechanism provided by TCP / IP for copying a file

from one host to another. It uses the services offer by TCP and so is reliable and secure. It establishes

two connections (virtual circuits) between the hosts, one for data transfer and another for control

information.

104. What are major types of networks and explain?

1. Server-based network: provide centralized control of network resources and rely on server

computers to provide security and network administration

2. Peer-to-peer network: computers can act as both servers sharing resources and as clients

using the resources.

105. What are the important topologies for networks?

1. BUS topology: In this each computer is directly connected to primary network cable in a

single line.

Advantages: Inexpensive, easy to install, simple to understand, easy to extend.

2. STAR topology: In this all computers are connected using a central hub.

Advantages: Can be inexpensive, easy to install and reconfigure and easy to trouble shoot

physical problems.

3. RING topology: In this all computers are connected in loop. Advantages: All computers have

equal access to network media, installation can be simple, and signal does not degrade as

much as in other topologies because each computer regenerates it.

106. What is mesh network?

A network in which there are multiple network links between computers to provide multiple paths for

data to travel.

107. What is difference between baseband and broadband transmission?

In a baseband transmission, the entire bandwidth of the cable is consumed by a single signal. In

broadband transmission, signals are sent on multiple frequencies, allowing multiple signals to be sent

simultaneously.

108. Explain 5-4-3 rule?

In a Ethernet network, between any two points on the network ,there can be no more than five

network segments or four repeaters, and of those five segments only three of segments can be

populated.

109. What MAU?

In token Ring , hub is called Multistation Access Unit(MAU).

110. What is the difference between routable and non- routable protocols?

Routable protocols can work with a router and can be used to build large networks. Non-Routable

protocols are designed to work on small, local networks and cannot be used with a router.