Questions and Answers of Computer Communications

What key factors affect channel capacity?
Define channel capacity.
What is the relationship between a signal’s spectrum and its bandwidth?
Define fundamental frequency.
What is the relationship between the wavelength and frequency of a sine wave?
How many radians are there in a complete circle of 360 degrees?
What are three important characteristics of a periodic signal?
Differentiate between an analog and a digital electromagnetic signal.
Use poll() function and socket programming to receive out-of-band data. Out-ofband data is also called urgent data in TCP, and is often received with first priority via a separate data stream. Hint:
Modify the server program from Exercise 2.4 to set the TCP window size for the server socket. Hint: Set the SO_RCVBUF size through a call to setsockopt(). Be aware that setting the TCP window size in
Write a stream-based echo server and a client sending messages to it, and receiving back each message in turn. Hint: Modify the stream-based TCP client and server programs in this chapter or similar
How to broadcast a message on the Internet? Two questions need to be answered:What address should be used as the broadcast address. How to send data to the broadcast address? A broadcast address is
Write a sockets program to get a host name for a given IP address.
Determining a local machine’s IP address is useful when you are handling network communication tasks. Write code to find the IP address of a local machine. Hint: You may use some public DNS, for
This problem concerns material in Appendix E. Based on the principles enunciated in Table E.1.a. Design an architecture with eight layers and make a case for it.b. Design one with six layers and make
We have seen that in order to deal with lost packets, TFTP implements a timeoutand-retransmit scheme, by setting a retransmission timer when it transmits a packet to the remote host. Most TFTP
In order to be able to retransmit lost packets, TFTP must keep a copy of the data it sends. How many packets of data must TFTP keep at a time to implement this retransmission mechanism?
The TFTP specification (RFC 1350) states that the transfer identifiers (TIDs) for a connection should be randomly chosen, so that the probability that the same number is chosen twice in immediate
A user on a UNIX host wants to transfer a 4000-byte text file to a Microsoft Windows host. In order to do this, he transfers the file by means of TFTP, using the netascii transfer mode. Even though
What is the limiting factor in the time required to transfer a file using TFTP?
The previous version of the TFTP specification, RFC 783, included the following statement:All packets other than those used for termination are acknowledged individually unless a timeout occurs.The
Why does the TCP header have a header length field while the UDP header does not?
Why is UDP needed? Why can’t a user program directly access IP?
In Figure 2.5, exactly one protocol data unit (PDU) in layer N is encapsulated in a PDU at layer 1N - 12. It is also possible to break one N-level PDU into multiple 1N - 12-level PDUs (segmentation)
A broadcast network is one in which a transmission from any one attached station is received by all other attached stations over a shared medium. Examples are a bustopology local area network, such
Two blue armies are each poised on opposite hills preparing to attack a single red army in the valley. The red army can defeat either of the blue armies separately but will fail to defeat both blue
List the major disadvantages with the layered approach to protocols.
a. The French and Chinese prime ministers need to come to an agreement by telephone, but neither speaks the other’s language. Further, neither has on hand a translator that can translate to the
Using the layer models in Figure 2.15, describe the ordering and delivery of a pizza, indicating the interactions at each level.
Compare the address space between IPv4 and IPv6. How many bits are used in each?
Does all traffic running on the Internet use TCP?
Which version of IP is the most prevalent today?
What is a router?
What are some advantages to layering as seen in the TCP/IP architecture?
What is TCP/IP?
What is a protocol data unit (PDU)?

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