Set - 3

Question 11 :

What are Digrams and Trigrams?

Answer :

The most common two letter combinations are called as digrams. e.g. th, in, er, re and an. The most common three letter combinations are called as trigrams. e.g. the, ing, and, and ion.

Question 12 :

What is the HELLO protocol used for?

Answer :

The HELLO protocol uses time instead of distance to determine optimal routing. It is an alternative to the Routing Information Protocol.

Question 13 :

What is the minimum and maximum length of the header in the TCP segment and IP datagram?

Answer :

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

Question 14 :

What do you meant by "triple X" in Networks?

Answer :

The function of PAD (Packet Assembler Disassembler) is described in a document known as X.3. The standard protocol has been defined between the terminal and the PAD, called X.28; another standard protocol exists between the PAD and the network, called X.29. Together, these three recommendations are often called "triple X".

Question 15 :

What is attenuation?

Answer :

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