Consider the grammar defined by the following production rules, with two operators * and +

$$\eqalign{ & S \to T*P \cr & T \to U\,|\,T*U \cr & P \to Q + P\,|\,Q \cr & Q \to id \cr & U \to id \cr} $$

Which one of the following is TRUE?

In the diagram shown below, L1 is an Ethernet LAN and L2 is a Token-Ring LAN. An IP packet originates from sender S and traverses to R, as shown. The links within each ISP and across the two ISPs, are all point-to-point’ optical links. The initial value of the TTL field is 32. The maximum possible value of the TTL field when R receives the datagram is ____________.

Consider the store and forward packet switched network given below. Assume that the bandwidth of each link is 10⁶ bytes/sec. A user on host A sends a file of size 10³ bytes to host B through routers R1 and R2 in three different ways. In the first case a single packet containing the complete file is transmitted from A to B. In the second case, the file is split into 10 equal parts, and these packets are transmitted from A to B. In the third case, the file is split into 20 equal parts and these packets are sent from A to B. Each packet contains 100 bytes of header information along with the user data. Consider only transmission time and ignore processing, queuing and propagation delays. Also assume that there are no errors during transmission. Let T1, T2 and T3 be the times taken to transmit the file in the first, second and third case respectively. Which one of the following is CORRECT?

An IP machine Q has a path to another IP machine H via three IP routers R1, R2, and R3.

Q—R1—R2—R3—H

H acts as an HTTP server, and Q connects to H via HTTP and downloads a file. Session layer encryption is used, with DES as the shared key encryption protocol. Consider the following four pieces of information:

$$[I1]$$ The URL of the file downloaded by Q
$$[I2]$$ The TCP port numbers at Q and H
$$[I3]$$ The IP addresses of Q and H
$$[I4]$$ The link layer addresses of Q and H

Which of $$[I1]$$, $$[I2]$$, $$[I3]$$, and $$[I4]$$ can an intruder learn through sniffing at R2 alone?