Which of the following grammar rules violate the requirements of an operator grammar? P, Q, R are nonterminals, and r, s, t are terminals.

$$\eqalign{ & 1.\,P \to QR \cr & 2.\,P \to QsR \cr & 3.\,P \to \varepsilon \cr & 4.\,P \to QtRr \cr} $$

Choose the best matching between Group 1 and Group 2 :

Group –1

P. Data link layer
Q. Network layer
R. Transport layer

Group – 2

1. Ensures reliable transport of data over a physical point-to-point link
2. Encodes/decodes data for physical transimission
3. Allows end-to-end communication between two processes
4. Routes data from one network node to the next

Suppose that the maximum transmit window size for a TCP connection is 12000 bytes. Each packet consists of 2000 bytes. At some point of time, the connection is slow start phase with a current transmit window of 4000 bytes. Subsequently, the transmitter receiver two acknowledgments. Assume that no packet are lost and there are no time-outs. What is the maximum possible value of the current transmit window?

A TCP message consisting of 2100 bytes is passed to IP for delivery across two networks. The first network can carry a maximum payload of 1200 bytes per frame and the second network can carry a maximum payload of 400 bytes per frame, excluding network overhead. Assume that IP overhead per packet is 20 bytes. What is the total IP overhead in the second network for this transmission?