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<P>
<UL>
<UL>
<UL>
<LI>
<A HREF="#E68E133" >Chapter 2</A></LI>
<LI>
<A HREF="#E68E134" >Chapter 3</A></LI>
<LI>
<A HREF="#E68E135" >Chapter 4</A></LI>
<LI>
<A HREF="#E68E136" >Chapter 5</A></LI>
<LI>
<A HREF="#E68E137" >Chapter 7</A></LI>
<LI>
<A HREF="#E68E138" >Chapter 8</A></LI>
<LI>
<A HREF="#E68E139" >Chapter 9</A></LI>
<LI>
<A HREF="#E68E140" >Chapter 10</A></LI>
<LI>
<A HREF="#E68E141" >Chapter 11</A></LI>
<LI>
<A HREF="#E68E142" >Chapter 13</A></LI>
<LI>
<A HREF="#E68E143" >Chapter 14</A></LI></UL></UL></UL>
<HR ALIGN=CENTER>
<A ID="E67E8" NAME="E67E8"></A>
<H2 ALIGN=CENTER>
<CENTER>
<FONT SIZE=6 COLOR="#FF0000"><B>— Appendix F —</B>
<BR><B>Answers to Quizzes</B></FONT></CENTER></H2>
<BR>
<BR>
<A ID="E68E133" NAME="E68E133"></A>
<H3 ALIGN=CENTER>
<CENTER>
<FONT SIZE=5 COLOR="#FF0000"><B>Chapter 2</B></FONT></CENTER></H3>
<BR>
<OL>
<LI>Draw the layered architectures of both the OSI Reference Model and TCP/IP. Show how the layers correspond in each diagram.
<BR>
<BR>The layered architecture of both the OSI-RM and TCP/IP are shown in Figure 2.2.
<BR></LI>
<BR>
<LI>Show the layered Internet architecture, explaining each layer's purpose.
<BR>
<BR>The layers of the Internet architecture are shown in Figure 2.5.
<BR></LI>
<BR>
<LI>Show how a datagram is transferred from one network, through one or more gateways, to the destination network. In each device, show the layered architecture and how high up the layered structure the datagrams goes.
<BR>
<BR>This process is shown in Figure 2.6.
<BR></LI>
<BR>
<LI>Draw the IP header and an Ethernet frame, showing the number of bits used for each component. Explain each component's role.
<BR>
<BR>The IP header and Ethernet frame structure is shown in Figure 2.8. The text in that section explain the role of each component.
<BR></LI>
<BR>
<LI>Explain what an ARP Cache is. What is its structure and why is it used?
<BR></LI>
<BR>
</OL>
<P>The ARP cache is used to hold IP addresses and physical addresses The layout of an ARP cache is shown in Figure 2.10. Each row corresponds to one device, with four pieces of information for each device.
<BR>
<BR>
<A ID="E68E134" NAME="E68E134"></A>
<H3 ALIGN=CENTER>
<CENTER>
<FONT SIZE=5 COLOR="#FF0000"><B>Chapter 3</B></FONT></CENTER></H3>
<BR>
<OL>
<LI>Explain why IP is important to the proper transmission of data.
<BR>
<BR>IP's primary task is the addressing of datagrams. Without IP, routing information would have to be constructed at a higher layer in the architecture.
<BR></LI>
<BR>
<LI>Show the construction of the IP header and the meaning of each element within the header structure.
<BR>
<BR>The IP header is shown in Figure 3.1. The meaning of each field within the header is explained in the text accompanying the figure.
<BR></LI>
<BR>
<LI>ICMP headers are quite small. Show the structure of a typical message header and the meaning of the bits within it.
<BR>
<BR>The ICMP header is shown in Figure 3.4. The meaning of each field and their valid values are explained in the accompanying text.
<BR></LI>
<BR>
<LI>Explain the different EGP message formats and when they are used.
<BR>
<BR>There are four EGP message formats in use: neighbor acquisition and neighbor reachability (both of which indicate the presence and status of neighbor devices); poll (to verify that a neighbor is active); and error (for reporting error conditions).
<BR></LI>
<BR>
<LI>Show the EGP message format, explaining the contents of the header and the network reachability information.
<BR>
<BR>The format of the EGP message headers is shown in Figures 3.6 and 3.7. The text accompanying the figures explains the meaning of the fields within the header.
<BR></LI>
<BR>
</OL>
<BR>
<A ID="E68E135" NAME="E68E135"></A>
<H3 ALIGN=CENTER>
<CENTER>
<FONT SIZE=5 COLOR="#FF0000"><B>Chapter 4</B></FONT></CENTER></H3>
<BR>
<OL>
<LI>Draw a diagram showing the binding of port tables when three machines are sending information to each other.
<BR>
<BR>This is shown in Figure 4.3.
<BR></LI>
<BR>
<LI>Draw the TCP protocol data unit (PDU) and explain the meaning of each field.
<BR>
<BR>The TCP PDU is shown in Figure 4.5. The fields are all explained in the accompanying text.
<BR></LI>
<BR>
<LI>Use a diagram to show the signals involved with two machines establishing a TCP connection. Then, show how data is transferred. Finally, show the termination process.
<BR>
<BR>The diagrams for all three steps are shown in Figures 4.6, 4.7, and 4.8.
<BR></LI>
<BR>
<LI>What is a TCP connection table? How is it used?
<BR>
<BR>TCP uses a connection table to keep track of all the active connections. Each existing connection has an entry in the table that shows information about the end-to-end connection. The layout of the TCP connection table is shown in Figure 4.9.
<BR></LI>
<BR>
<LI>Draw the UDP header and explain the fields it contains.
<BR>
<BR>The UDP header is shown in Figure 4.10. The accompanying text explains the purpose of each field.
<BR></LI>
<BR>
<LI>What are the advantages of using UDP over TCP? When would you not want to use UDP?
<BR>
<BR>UDP is connectionless, hence a little faster. It is not as reliable as TCP, though, so is not useful for applications when a connection must be maintained for long periods or when reliability of transfer is important.
<BR></LI>
<BR>
</OL>
<BR>
<A ID="E68E136" NAME="E68E136"></A>
<H3 ALIGN=CENTER>
<CENTER>
<FONT SIZE=5 COLOR="#FF0000"><B>Chapter 5</B></FONT></CENTER></H3>
<BR>
<OL>
<LI>Explain what a network virtual terminal is.
<BR>
<BR>A network virtual terminal (NVT) is used to define both ends of a connection. It has a logical keyboard and a logical printer (display). NVTs are necessary to allow a connection to exist.
<BR></LI>
<BR>
<LI>Draw diagrams showing two- and three-party FTP sessions, indicating the port numbers used by each machine.
<BR>
<BR>These diagrams are shown in Figures 5.4 and 5.5.
<BR></LI>
<BR>
<LI>Why would you want to enable anonymous FTP access? Are there any reasons for disallowing it?
<BR>
<BR>Anonymous FTP access enables users to upload and download files to your system without having to log in. This can be useful when you want to share information without worrying about user IDs. Anonymous FTP should be disabled if you do not plan to share information globally, because there are several possible security concerns with a poorly administered anonymous FTP setup.
<BR></LI>
<BR>
<LI>TFTP enables files to be transferred without logging in. What problems can this cause?
<BR>
<BR>TFTP's capability to transfer files without a login can enable a remote user to transfer a file to or from your system without your specific knowledge, as long as the security system and file permissions are set to enable this. A well-run system controls TFTP's access considerably.
<BR></LI>
<BR>
<LI>What are the Berkeley Utilities?
<BR>
<BR>The Berkeley Utilities are a set of useful utility programs developed for TCP/IP at the University of California at Berkeley. The tools are known as the Berkeley Utilities in honor of their developers.
<BR></LI>
<BR>
</OL>
<BR>
<A ID="E68E137" NAME="E68E137"></A>
<H3 ALIGN=CENTER>
<CENTER>
<FONT SIZE=5 COLOR="#FF0000"><B>Chapter 7</B></FONT></CENTER></H3>
<BR>
<OL>
<LI>Define the role of gateways, routers, bridges, and brouters.
<BR>
<BR>A gateway performs routing functions between networks and can translate protocols. A bridge connects two or more networks using the same protocol. A router is a network device that forwards datagrams around the network. A brouter performs the functions of both the bridge and the router.
<BR></LI>
<BR>
<LI>What is a packet-switched network?
<BR>
<BR>A packet-switched network is one where all transfers of information are based on self-contained packets (like TCP/IP's datagrams).
<BR></LI>
<BR>
<LI>What is the difference between interior and exterior neighbor gateways?
<BR>
<BR>Interior gateways connect LANs of one organization, whereas exterior gateways connect the organization to the outside world.
<BR></LI>
<BR>
<LI>What are the advantages and disadvantages of the three types of routing tables?
<BR>
<BR>The three types of routing tables are fixed, dynamic, and fixed central. The fixed table must be manually modified every time there is a change. A dynamic table changes its information based on network traffic, reducing the amount of manual maintenance. A fixed central table lets a manager modify only one table, which is then read by other devices. The fixed central table reduces the need to update each machine's table, as with the fixed table. Usually a dynamic table causes the fewest problems for a network administrator, although the table's contents can change without the administrator being aware of the change.
<BR></LI>
<BR>
<LI>What is the HELLO protocol used for?
<BR>
<BR>The HELLO protocol uses time instead of distance to determine optimal routing. It is an alternative to the Routing Information Protocol.
<BR></LI>
<BR>
</OL>
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