30. Which layers are user support layers?
This is also a frequently asked question in networking job interview.
Answer: There are 3 different types of user support layers and they are:
a. Session Layer: The Session Layer manages the sequence and flow of events that initiate and tear down network connections. At Layer 5, it is built to support multiple types of connections that can be created dynamically and run over individual networks. examples include NFS, NetBIOS names, RPC, SQL.
b. Presentation Layer: This layer provides independence from differences in data representation (e.g., encryption) by translating from application to network format, and vice versa. examples include encryption, ASCII, EBCDIC, TIFF, GIF, PICT, JPEG, MPEG, MIDI.
c. Application Layer: The Application layer supplies network services to end-user applications. Network services are typical protocols that work with user’s data. For example, in a Web browser application, the Application layer protocol HTTP packages the data needed to send and receive Web page content. This Layer 7 provides data to (and obtains data from) the Presentation layer. examples include WWW browsers, NFS, SNMP, Telnet, HTTP, FTP
31. What is FDM, WDM, TDM?
Answer: 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.
WDM is conceptually the same as FDM, except that the multiplexing and demultiplexing involve light signals transmitted through fiber optics channel.
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.
32. How many types of wireless transmission are there?
Answer: Generally there are five types of wireless transmission. They are:
1. The Electromagnetic Transmission
2. Radio Transmission
3. Microwave Transmission
4. Infrared Transmission
5. Light Transmission
33. What is Piggy Backing?
Answer: A technique called piggybacking is used to improve the efficiency of the bidirectional protocols. When a frame is carrying data from A to B, it can also carry control information about arrived (or lost) frames from B; when a frame is carrying data from B to A, it can also carry control information about the arrived (or lost) frames from A.
34. Describe Classful Addressing
Answer: AIPv4 addressing uses the concept of classes. In classful addressing, the address space is divided into five classes: A, B, C, D, and E. We can find the class of an address when the given address is in binary notation or dotted-decimal notation.
35. What is the difference between physical topology and logical topology?
Answer: A physical topology describes how computers are connected with each others physically. While a logical topology describes how data is being transmitted over the physical topology.
36. What do you mean by Channelization in networks?
Answer: Channelization is a multiple-access method in which the available bandwidth of a link is shared in time, frequency, or through a code, between different stations. There are three basic approaches to achieve channelization.
37. What is the signal bouncing issue and how it can be solved?
Answer: Signal bouncing issue occurs in bus topology. Bus topology uses a coaxial cable to connect the computers. In this topology when the computer sends a signal, the signal travels in both directions from sending computer. When this signal reaches the end of the cable, it bounces back and returns in the original direction. This is known as signal bouncing issue. To solve this issue we should use the terminator. Terminator absorbs the signals when they reach to it. This will prevent the signal bouncing issue.