Top Most Networking Interview Questions Part – 5
1.Define cyclic redundancy check (CRC).
C RC appends a sequence of redundant bits derived from binary division to the data unit. The divisor in the CRC generator is often represented as an algebraic polynomial.
2.What is hamming code?
The hamming code is an error correction method using redundant bits. The number of bits is a function of the length of the data bits. In hamming code for a data unit of m bits,we use the formula 2r >= m+r+1 to determine the number of redundant bits needed. By rearranging the order of bit transmission of the data units,the hamming code can correct burst errors.
3.Define stop and wait ARQ.
In stop and wait ARQ,the sender sends a frame and waits for an acknowledgement from the receiver before sending the next frame.
4.What do you mean by network control protocol?
Network control protocol is a set of protocols to allow the encapsulation of data coming from network layer protocol that requires the services of PPP
5.What do you mean by CSMA?
To reduce the possibility of collision CSMA method was developed. In CSMA each station first listen to the medium (Or check the state of the medium) before sending. It can’t eliminate collision.
6.What do you mean by Bluetooth?
It is a wireless LAN technology designed to connect devices of different functions such as telephones,notebooks,computers,cameras,printers and so on.
7.What is IP address?
The internet address (IP address) is 32bits that uniquely and universally defines a host or router on the internet.The portion of the IP address that identifies the network is called netid. The portion of the IP address that identifies the host or router on the network is called hostid.
8.What do you mean by ALOHA ?
It is the method used to solve the channel allocation problem .It is used for:
i)ground based radio broadcasting
ii)In a network in which uncoordinated users are competing for the use of single channel.
It is of two types:
1.Pure aloha
2.Slotted aloha
9.What is Firewalls?
It is an electronic downbridge which is used to enhance the security of a network. It’s configuration has two components.
i)Two routers
ii)Application gateway the packets travelling through the LAN are inspected here and packets meeting certain criteria are forwarded and others are dropped.
10.What is Repeaters ?
A receiver receives a signal before it becomes too weak or corrupted,regenerates the original bit pattern,and puts the refreshed copy back onto the link.It operates on physical layer of OSI model.
11.What is Bridges?
They divide large network into smaller components.They can relay frames between two originally separated LANs.They provide security through partitioning traffic.They operate on physical and data link layer of OSI model.
12.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.
13.What is FDM?
FDM is an analog technique that can be applied when the bandwidth of a link is greater than the combined bandwidths of the signals to be transmitted.
14.What is WDM?
WDM is conceptually the same as FDM,except that the multiplexing and demultiplexing involve light signals transmitted through fiber optics channel.
15.What is TDM?
TDM is a digital process that can be applied when the data rate capacity of the transmission medium is greater than the data rate required by the sending and receiving devices.
16.List the steps involved in creating the checksum.
a. Divide the data into sections
b. Add the sections together using 1’s complement arithmetic
c. Take the complement of the final sum,this is the checksum.
17.Compare Error Detection and Error Correction:
The correction of errors is more difficult than the detection. In error detection,checks only any error has occurred. In error correction,the exact number of bits that are corrupted and location in the message are known. The number of the errors and the size of the message are important factors.
18.What are the protocols in application layer ?
The protocols defined in application layer are
• TELNET
• FTP
• SMTP
• DNS
19.What are the protocols in transport layer ?
The protocols defined in transport layer are
• TCP
• UDP
20.What do you mean by client server model ?
In client server model ,the client runs a program to request a service and the server runs a program to provide the service.These two programs communicate with each other. One server program can provide services to many client programs.
21.What is TELNET ?
TELNET is a client –server application that allows a user to log on to a remote machine,giving the user access to the remote system. TELNET is an abbreviation of terminal Network.
22.What is Hypertext Transfer Protocol(HTTP) ?
It is the main protocol used to access data on the World Wide Web .the protocol transfers data in the form of plain text,hypertext,audio,video,and so on. It is so called because its efficiency allows its use in a hypertext environment where there are rapid jumps from one document to another.
23.What is World Wide Web ?
World Wide Web is a repository of information spread all over the world and linked together.It is a unique combination of flexibility,portability,and user-friendly features .The World Wide Web today is a distributed client-server service,in which a client using a browser can access a service using a server.The service provided is distributed over many locations called web sites.
24.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.
25.What is RAID?
A method for providing fault tolerance by using multiple hard disk drives.
26.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.
27.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.
28.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.
29.What are major types of networks and explain?
Server-based network: provide centralized control of network resources and rely on server computers to provide security and network administration
Peer-to-peer network: computers can act as both servers sharing resources and as clients using the resources.
30.What are the important topologies for networks?
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.
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.
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.