Network+ Guide to Networks, 4 th Edition

Chapter 11 Solutions

Review Questions


1. Suppose a large corporation has leased an entire Class A network range of IP addresses, which offers over 16 million potential host addresses. However, the company has only 20,000 nodes on its global network. How could this company benefit from subnetting?

d. Subnetting would enable the company to subdivide the network into distinct logical parts, thus simplifying traffic and address management.


2. Convert the following subnet mask into its dotted-decimal equivalent: 11111111

11111111 11111000 00000000.



3. What is the default subnet mask for a Class A network?



4. A node on a network has an IP address of and its subnet mask is 255. 248.0.0. What type of subnetting has been used on this network?

c. supernetting


5. On a network with an IP address of (or 10001100 10000101 00011100 01001000) and a subnet mask of (or 11111111 11111000 00000000 00000000), what is the network ID?

a. (or 10001100 10000000 00000000 00000000)


6. As a networking consultant, you've been asked to help expand a client's TCP/IP network. The network administrator tells you that the network ID is subnetted as On this network, how many bits of each IP address are devoted to host information?

b. 6


7. If you worked on an older network that could not interpret classless addressing, and your network ID was, what is the theoretical maximum number of different subnets you could create on this network?

d. 254


8. You have decided to create 254 subnets on your Class B network. What subnet mask will you use to accomplish this?



9. If you subdivide your Class B network into 254 subnets, what is the maximum number of hosts you can assign to any single subnet?

b. 254


10. Your company has leased a Class C network whose network ID is You want to create 16 subnets within this network. One of the subnets will have an extended network prefix of What will be the broadcast address for this subnet? Hint: If you know the number of hosts per subnet, you can easily determine the broadcast address.)



11. Your workstation's IP address is and your supervisor's workstation's IP address is When you send data from your workstation to your supervisor's workstation, what is the most likely IP address of the first default gateway that will accept and interpret your transmission?



12. Suppose you have established a small office network. The office connects to the Internet through a router connected to a DSL connection supplied by your local telecommunications carrier. Your carrier assigns a single IP address to your DSL connection. However, your office network consists of six workstations and one printer. Which of the following addressing techniques can you implement that will allow all your LAN's nodes to communicate with each other using different IP addresses, yet still use the Internet?

c. NAT


13. Suppose you have a home network consisting of two computers running Windows XP Home Edition and one computer running Windows 2000. You have a dial-up connection to the Internet through your ISP, but you only want to set up dial-up networking on one of the computers. Which of the following would allow all three computers to use the same dial-up Internet connection?

c. ICS


14. What is SMTP's primary function?

d. to transport mail from one mail server to another


15. You have offered to help a friend set up her e-mail client software. She knows the e-mail address that her ISP assigned her. Assuming she can connect to the Internet and browse Web pages without trouble, what further information will you need before you can properly configure her e-mail software to retrieve her messages?

b. SMTP server name


16. Which two of the following are benefits of using IMAP4 relative to POP3?

b. It allows users to review and delete mail without downloading it from the mail server.

e. It enables multiple users to easily share a central mailbox.


17. Suppose you want to send a picture of your new car in an e-mail message to your friend. To view the picture, what type of e-mail client must your friend have?

c. MIME-capable


18. What Network layer protocol does the traceroute utility use to obtain its information about paths between a source and destination?



19. Which of the following commands allows you to view the routing table on your workstation?

a. netstat -r


20. When you use the traceroute command to trace the path from your office workstation to a popular Web site, what is the first hop the traceroute command will display?

b. your default gateway's IP address


21. Suppose you are running a small Windows-based peer-to-peer network at home to share files between computers. You have modified the properties of a folder on the hard disk of the computer in your office to share it in an unrestricted manner over the network. To see if your shared folder configuration worked, you ask your friend to attempt to open your computer's folder from a computer in the basement of your house. Without further communication with your friend, which two of the following methods can you use to determine whether he successfully opened the folder?

b. by running the netstat utility and checking whether the IP address of the computer in the basement appears in the list of connected nodes

c. by running the nbtstat utility with the -s switch and checking whether the NetBIOS name of the computer in the basement appears in the list of connected



22. If you know that your colleague's TCP/IP host name is JSMITH, and you need to find out his IP address, which of the following commands should you type at your shell prompt or command prompt?

a. nslookup jsmith


23. Suppose your office's only DNS server was down, and you wanted to view the DNS address record for your company's domain. Which of the following TCP/IP utilities would allow you to do this?

a. dig


24. What utility might you use to find out whether your ISP's router is especially slow on a particular afternoon?

c. traceroute


25. What command would you use to list the TCP/IP configuration for all three of the NICs in your Linux server?

d. ifconfig -a


Hands-On Projects


Project 11-1

This project offers students the opportunity to configure an e-mail client. To complete the project, student workstations must be installed with the Eudora Light e-mail program, which is available at no cost from Qualcomm at: Students must have at their disposal a working e-mail account and also know the e-mail settings (such as password and outgoing/incoming mail server names) to send and retrieve e-mail using this account. At the end of this project, students test the e-mail client settings they've made by attempting to send mail. Therefore, each workstation requires Internet access.

Steps 1 – 11: Students enter the correct Eudora Light client parameters and attempt to retrieve mail.

Steps 12 – 18: Students change the SMTP server name to be incorrect and attempt the send a message. The error message returned should be something similar to “Error getting network address for ‘ ' Cause: host not found (11001)” where is the name of the incorrect SMTP server students entered in Step 14.

Step 19: Students restore the correct SMTP server setting.


Project 11-2

In this project students experiment with the netstat and traceroute (or tracert) TCP/IP utility. This project is written to work with UNIX, Linux, and Windows XP systems that are connected to the Internet. Command responses will vary according to the network and type of workstation students use.


Project 11-3

In this project, students use the nslookup utility to determine a domain's mail server address, then perform tests to verify that the mail server is working. At the end of the project, they use the whois utility from ARIN's Web site to determine . This project is written to work with UNIX, Linux, and Windows XP systems that are connected to the Internet and have a modern browser installed.

Step 2: At the time of this writing, the IP address returned was

Step 4: At the time of this writing, the name server host names and addresses returned were: nameserver = nameserver = internet address = internet address =

Step 5: At the time of this writing, the mail server hostnames and addresses returned were: MX preference = 10, mail exchanger = MX preference = 5, mail exchanger = nameserver = nameserver = internet address = internet address =

(Answers to other steps will vary, depending on the domain the student chooses to look up.)


Case Projects


Case Project 11-1

First, InterGuard should change from using statically assigned IP addresses to using DHCP-assigned addresses for all its network clients. This will reduce the effort necessary to ensure each node has a unique network address and will make future network expansion simpler. Even better would be to implement NAT in conjunction with DHCP, so that private IP addresses can be automatically assigned to clients in the internal LAN, and then public IP addresses assigned to transmissions that cross the LAN boundary headed for a public network, such as the Internet. Adding DHCP and NAT to the network might not require the purchase of new hardware, if InterGuard has a server running an NOS that can manage DHCP (and all modern NOSs are capable of that) and a router that can manage NAT. A simple network diagram would show the clients from different areas of the company connecting to five switches, which then connect to a router. This router could be the one that runs NAT (and, by the way, firewall services), or a second router could be added to separate the private and public parts of the network. A server would probably be connected to one of the switches behind the router.


Case Project 11-2

To meet its employees' needs, InterGuard's mail server would need to be capable of supporting the IMAP e-mail protocol. Most modern mail server software can do this. In the network diagram, the mail server could be connected to one of the switches or routers. Unless ports are reassigned by the network administrator, clients will require access to the IMAP port on the mail server, which is port number 143.


Case Project 11-3

In reality, the best way to identify a node that is generating heavy traffic would be to use a protocol analyzer. However, some information can be gleaned by using the netstat utility on a device (for example, a server) that is the victim of such heavy traffic. The command netstat –e will give broad traffic statistics for the host. The command netstat –a will list all connections to the host, their local ports, foreign hostnames and ports, and the protocol in use. The command netstat –n will list the foreign IP address for every connection as well. The command netstat -b will list every connection, its local port and foreign address and port, its process ID and filenames involved, and the protocol used.