An IP router implementing Classless Inter-domain Routing (CIDR) receives a packet with address 131.23.151.76. The router’s routing table has the following entries:

The identifier of the output interface on which this packet will be forwarded is ______.

Every host in an IPv4 network has a 1-second resolution real-time clock with battery backup. Each host needs to generate up to 1000 unique identifiers per second. Assume that each host has a globally unique IPv4 address. Design a 50-bit globally unique ID for this purpose. After what period (in seconds) will the identifiers generated by a host wrap around?

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?

In an IPv4 datagram, the M bit is 0, the value of HLEN is 10, the value of total length is 400 and the fragment offset value is 300. The position of the datagram, the sequence numbers of the first and the last bytes of the payload, respectively are