UIDL abbreviates "precise-ID listing". When a POP3 purchaser problems the UIDL command, the server responds with the specific message ID for all of the messages present in the users mailbox. This command is useful for "down load and hold". By maintaining a file that lists the messages retrieved in in advance sessions, the consumer can use the UIDL command to determine which messages at the server have already been visible.

Problem thirteen.

A) For a given enter of area name (including ccn.Com), IP deal with or community administrator call, whois database can be used to discover the corresponding registrar, whois server, dns server, etc.

F) An attacker can use the whois database and nslookup tool to decide the IP address tiers, DNS server addresses, and so on. For the target organization.

G) If below an attack a sufferer can analyze the supply address of packets, the sufferer can then use whois to attain records about domain from which attack is coming and likely inform the administrators of the foundation area.

Problem 14. No. Because the hyperlink is complete duplex, you've got 128 kbps in each direction, and the importing does now not interfere with the downloading.

Problem 15. There are N nodes in the overlay network. There are N(N-1)/2 edges.

Problem 16. A) In this situation, every of the five Gnutella customers immediately learns that it has one much less neighbor. Consider such a 5 customers, called, Bob. Suppose Bob has simplest 3 friends after X drops out. Then Bob desires to establish a TCP reference to every other peer. Bob must have a sparkling list of active friends; he sequentially contacts friends on this listing until one accepts his TCP connection attempt.

1.1 Is the network peer-to-peer or client-server network? (1 Mark) 1.2 assume that the brokerage software encrypt that data before after manipulation and before storing them. Which OSI layer is responsible of encrypting these data?(1 mark) 1.2 write two reasons why we need to keep network diagram up to date. (1 mark) Q2. Draw a network diagram that shows how they can connect the two floors together. (3 Marks) Q3. Answer the following questions: 3.1 What type of the cables and networking devices can be used to connect the two floors? (2 Marks) 3.2what will be the physical topology and the logical topology of the network?(2 marks) Q4. Answer the following questions Assume that one of the devices has the IP address: 120.64.55.1/10 4.1 What is the network address? (0.5) 4.2 What is the host address? (0.5) 4.3 What is the subnet mask? (0.5) 4.4 name one of the network services that the network provides.(0.5)