The part of the IP address that is the same for all computers on a network is called the Host ID.

True / False Questions
 

36. (p. 156) The part of the IP address that is the same for all computers on a network is called the Host ID.
FALSE

37. (p. 162) If the first octet of the IP address begins with 110 (110xxxxx), the system belongs to a Class C network.
FALSE

38. (p. 167) One of the downsides of subnetting is that you will need to waste subnets.
TRUE

39. (p. 162) On a/24 network you can have 256 hosts.
FALSE

40. (p. 174) Not only does DHCP give out IP addresses, but it can also give out additional IP information, such as subnet mask and default gateway.
TRUE

41. (p. 175) On a Linux system, you can renew a DCHP address by using the command ipconfig/renew.
FALSE

42. (p. 175) When a computer gives itself an Automatic Private IP Address (APIPA), it also includes a valid default gateway address.
FALSE

43. (p. 173) Every time a DHCP client boots up, it sends out a special DHCP discovery packet.
TRUE

44. (p. 164) The only goal of subnetting is efficient use of all the IP addresses.
FALSE

45. (p. 176) The term BOOTPS refers to a BOOTP server.
TRUE

46. (p. 146) The Link layer is where most of the activity happens in the TCP/IP protocol suite.
FALSE

47. (p. 148) The Protocol Data Unit for the TCP protocol is called a segment.
TRUE

48. (p. 146) IP is a Transport layer protocol.
FALSE

49. (p. 147) UDP is a connection-oriented protocol.
FALSE

50. (p. 149) There are four fields in a UDP datagram.
TRUE

Fill in the Blank Questions
 

51. (p. 151) IP addresses are normally written as four decimal values separated by __________________
periods or dots

52. (p. 152) Each of the four parts of an IP address is called a binary __________________ because of the number of digits contained in each part.
octet

53. (p. 152) To do numeric conversions easily, use a calculator that has __________________ mode.
scientific or programmer

54. (p. 156-157) A(n) __________________ gives a router the actual instructions telling it what to do with incoming packets and where to send them.
routing table

55. (p. 156) A TCP/IP network uses a(n) __________________ to interconnect to other TCP/IP networks.
router

56. (p. 160) A TCP/IP host uses the __________________ protocol to learn the MAC address of a host based on its IP address.
Address Resolution Protocol (ARP)

57. (p. 156) The IP address of a router's connection to your LAN is known as the __________________.
default gateway

58. (p. 162) In order to connect to the Internet, a computer on a TCP/IP LAN must be configured with an IP address, subnet mask, and __________________.
default gateway

59. (p. 157) To distinguish between local and remote IP addresses, every system on a TCP/IP network needs a special binary value called the __________________.
subnet mask

60. (p. 163) If the last octet of a Class C IP address consists of all zeroes, you are looking at the __________________.
network ID

61. (p. 163) When viewed in binary notation, no host ID can be either all __________________ or all __________________.
zeroes; ones

62. (p. 163) When viewed in binary notation, the first octet of a Class B network begins with __________________.
10

63. (p. 164) Most network techs represent subnet mask as a "/" character followed by a number equal to the number of __________________ in the subnet mask.
ones

64. (p. 164) After you determine how many subnets you need to create, start with the given subnet mask and move it to the __________________ as many places as you need to get the required number of subnets.
right

65. (p. 152) The subnet mask for a Class A, Class B, or Class C network always starts immediately after a(n) __________________.
period or dot

66. (p. 156) In its binary form, a full network ID always ends in __________________.
zero

67. (p. 173) A DHCP __________________ is a range of IP addresses that a DHCP server can give out to requesting clients.
scope

68. (p. 162) The __________________ is the central organization that tracks and disperses IP addresses.
Internet Assigned Numbers Authority (IANA)

69. (p. 155) The part of the IP address shared by all the computers on a network segment is called the __________________.
Network ID

70. (p. 156) The part of an IP address that is unique for each system on a subnet is called the __________________.
Host ID

71. (p. 165) Subnetting only makes sense in __________________ notation.
binary

72. (p. 151) The current 32-bit IP specification is __________________.
IPv4 (Internet Protocol version 4)

73. (p. 174) A(n) __________________ is both the acceptance of IP settings from a DHCP client and the amount of time that the client may hold the IP configuration before it must renew.
DHCP lease

74. (p. 173) DHCP stands for __________________.
Dynamic Host Configuration Protocol

75. (p. 164) The cornerstone to subnetting lies in the __________________.
subnet mask

76. (p. 164) To subnet, you take an existing/8,/16, or/24 subnet and __________________ the subnet mask by adding more ones (removing the same number of zeroes in the host portion).
extend

77. (p. 152) In a LAN running TCP/IP, every computer has both an IP address and a(n) __________________.
MAC address

78. (p. 176) If pinging the address 127.0.0.1 fails, it's likely that the __________________ has a problem.
NIC

79. (p. 155-156) The two parts that make up an IP address are split into the ___________ and the _____________.
network ID; the host ID

80. (p. 167) With TCP/IP, each subnet will have _________ host IDs than the larger network from which it was created.
fewer

81. (p. 147) __________ is a connectionless protocol that operates at the Transport layer.
UDP

82. (p. 148) Over _________ percent of all TCP/IP applications use TCP as their transport protocol.
95

83. (p. 148) __________ signify which Application layer protocol receives data from the Transport layer.
Ports

84. (p. 146) The __________ layer is concerned with logical addressing.
Internet

85. (p. 148) The protocol data units (PDUs) at the transport layer are __________ and _________.
segments; datagrams

Essay Questions
 

86. (p. 153) Describe what you would do on a Windows XP or Vista system to see its IP address. 

To see the IP address on a Windows system, I would open a command prompt and run the ipconfig command. To see the most useful information, I would enter it as follows: ipconfig/all. [The reason I would not use the GUI tool Internet Protocol Version 4 (TCP/IPv4) Properties dialog box is that this will not show the actual IP configuration if the computer is a DHCP client.]

87. (p. 176) What is the loopback address and what is its purpose? 

The loopback address is 127.0.0.1, and it is assigned to the software loopback interface of a NIC. It has many purposes. The most common is allowing you to test a NIC's capability to send and receive packets. To do this in Windows, open a command prompt and enter the command ping 127.0.0.1.

88. (p. 176) Why would you use private IP addresses? 

The private IP addresses, those in the 10.0.0.0 to 10.255.255.255 range or 172.16.0.0to 172.31.255.255 range, or the 192.168.0.0 to 192.168.255.255 range, are very useful. Since all routers destroy packets containing these addresses, they can never be used on the Internet, so they are useful in hiding your private network from an attached network, such as the Internet.

89. (p. 175) What does it mean if a system's IP address is within the 169.254/16 network? 

If a system's IP address is within the 169.254/16 network, it means that it is using an Automatic Private IP Address (APIPA), which means that it was unable to contact a DHCP server to receive IP information, and assigned an address to itself from the APIPA range.

90. (p. 175) What would you do if you discovered that your computer was using APIPA on a network that has a functioning DHCP server (assume you are working with a computer running Windows)? 

The first thing I would do is to manually initiate a renewal of the DHCP lease by opening a command line and using the following command: ipconfig/renew. If this did not work, I would assume that the NIC needed encouragement to release the old address, and I would run this command: ipconfig/release. I would follow that command with: ipconfig/renew.

91. (p. 159) Define the term subnet mask. 

A subnet mask is a string of ones followed by some number of zeroes, always totaling exactly 32 binary digits. It is part of the basic IP information required by every host on a TCP/IP network, and it delineates the two portions of an IP address: the network ID and the host ID.

92. (p. 160) Given the IP address of a destination on the local LAN, how does a TCP/IP host discover the MAC address in order to send an Ethernet frame? 

If a TCP/IP host knows the IP address, but does not know the MAC address of a destination computer on the local network, it can use address resolution protocol (ARP) to discover the MAC address. To do this, it broadcasts a special packet, containing its own IP address and MAC address and the IP address of the destination computer. The computer with the IP address matching the destination IP address will respond with an ARP packet containing its IP address as well as its MAC address.

93. (p. 161) Describe how you would display the ARP table on a Windows computer. 

To view the ARP table on a Windows computer, I would open a command prompt and type the following command: arp -a.

94. (p. 156) Describe briefly what a default gateway is on a TCP/IP network and what it does for you. 

A default gateway is the IP address of a router on your network. Having a router on your network, allows computers on the network to send traffic beyond your LAN, even to the Internet.

95. (p. 156) Describe the two parts of an IP address and the reason they are used. 

The two parts of an IP address are the network ID and the host ID. They are part of why you can communicate with computers beyond your local network because they identify both the network and the host on that network.

96. (p. 165) When determining the number of subnets you will have, why must you subtract two from the total that appears to be possible, based on the number of bits you have borrowed from the host IDs of a Class network address? 

You must always subtract two subnets because you cannot have a network ID extension of all zeroes (reserved for the network itself), nor can you have a network ID extension of all ones (reserved for the broadcast address).

97. (p. 173) How would you set up a Windows system to use DHCP? 

To set up a Windows system to use DHCP, I would open the Internet Protocol Version 4 (TCP/IP) Properties dialog box and select the radio button next to Obtain an IP address automatically.

98. (p. 173) What is DHCP and why would you use it? 

DHCP, or Dynamic Host Configuration Protocol, is a protocol that allows hosts to automatically receive IP addressing information from a DHCP server. Most computer users receive their IP address configuration in this manner because it is automated and does not require that someone visit every computer to configure the IP information. It also allows an administrator to make changes to the IP addressing of a network centrally, once again, without visiting every computer.

99. (p. 162) If the IP address of a system is 184.222.4.36/16, what class address is it? 

An address of 184.222.4.36/16 is a Class B address because the value of the first portion of the address is within the Class B range of 128 to 191.

100. (p. 165-167) Given a block of addresses with a/28 subnet mask, calculate the number of useful host IDs available on this subnet and explain how you arrived at your answer. 

Given a subnet mask of/28, there are just 14 available host IDs for this subnet. The formula I used is Error! Hyperlink reference not valid.. In this case there are four zeroes in the subnet mask, so the calculation would look like this: 2⁴-2 = 14.

101. (p. 164) What are the two goals of subnetting? 

The two goals of subnetting are efficiency and making multiple network IDs from a single network ID.

102. (p. 170) Explain the two ways that an IP address is assigned to a NIC. 

The two ways in which an IP address is assigned to a NIC are static and dynamic. A static address assignment requires that someone manually enters the IP address into the proper utility in the operating system. For instance, you would use the Internet Protocol Version 4 (TCP/IPv4) Properties dialog box to assign a static IP address in Windows. To assign an address dynamically, someone must first configure a Dynamic Host Configuration Protocol (DHCP) server on the LAN, giving it a scope of IP addresses and other IP configuration information to assign to DHCP hosts on the network. Then other computers on the network must be configured to be DHCP clients. To do this in Windows Vista, go to the Internet Protocol Version 4 (TCP/IP) Properties dialog box and select the radio button next to Obtain an IP address automatically.

103. (p. 145) Why would someone say that TCP/IP scales well? Using general terms, elaborate on this statement. 

When someone says that TCP/IP scales well, they mean that it can be used for small, simple networks, and for large networks made up of interconnected networks—even the largest of them all, the Internet. The secret is in the IP address, which contains both a network address (the network ID) and an individual host address (the host ID). This is a basis for sending IP packets across multiple networks and having them arrive at the correct network and host, although we have not yet gotten into the real magic of all this, routers.

104. (p. 155) For networks using TCP/IP, how can you identify computers that belong to the same subnet? 

The Network ID of the IP address will be the same for all the computers on the same subnet. The Network ID can be determined by comparing the IP address with the subnet mask.

105. (p. 170) Define CIDR, including the full name for this acronym and why it is used. 

Classless Inter-Domain Routing (CIDR) is a method for generating blocks of IP addresses out of the original Classful IP networks—Class A, Class B, and Class C. The reason for using CIDR is to extend the use of the IPv4 address space and delay the inevitable day when there will be no more unallocated addresses.

106. (p. 165) Describe the three rules for subnetting a network ID. 

The first rule for subnetting a network ID is that you must start with a beginning subnet mask, extending the network ID extension (NE) until you have the number of subnets you need. The second rule is that you cannot have an NE of all zeroes or all ones. The third rule for subnetting a network ID is that you cannot have a single-character network ID extension. You must start by moving the subnet mask at least two binary digits to the right.

107. (p. 176) What port number is associated with DHCP and BOOTP servers? 

The port number 67 is associated with DHCP and BOOTP servers.

108. (p. 173-174) Describe the normal DHCP process, including the types of messages exchanged. 

Every time a DHCP client boots up, it sends out a DHCP discovery packet using a broadcast address. Upon receiving this message, the DHCP server on the network would respond with a DHCP offer. The client, on receiving the offer, responds with a DHCP request accepting the offer. The server responds with a DHCP acknowledge, and lists the client MAC address and assigned IP address in a database. The client accepts the IP data and responds with a DHCP lease, which is the amount of time the DHCP server is allowing the client to use the IP information before it must renew, repeating the process.

109. (p. 172) You are configuring a small network with static IP addresses. Once you have at least two of the systems configured, describe the simple test you will make to test the ability of the computers to communicate with each other. 

After configuring at least two of the computers with IP addressing information, I would use the ping command to test the connectivity between the computers. In fact, once all of the computers are configured, I could simply sit at one computer and ping the address of each of the others in turn.

110. (p. 156) Although not an actual standard or a rule, what is a common principle for assigning a default gateway (router) address on a network? 

A common principle or practice is to give the default gateway the first IP address in the network ID.

111. (p. 172) After setting static IP information on several computers, if you discover that they cannot communicate, what is the most likely cause? 

If a computer with a static IP configuration fails to communicate, first check the manually configured IP settings, because a typo in the IP configuration is the most likely cause of this problem.

112. (p. 163) Why can you not create a host ID that is all zeroes? 

You cannot have a host ID that is all zeroes because all zeroes in the host port identifies an address as a network address.

113. (p. 164) What practice allows network techs to break their IP address networks into smaller sets of network addresses? 

The practice of subnetting an IP network address allows a network tech to break it up into small sets of network addresses including host IDs for each network.

114. (p. 176) Your Linux system appears to have a DHCP problem. You decide that you should release and renew the DHCP lease, and you begin by running the following command: SUDO IFCONFIG ETH0 DOWN. That should release the current lease, but the command results in an error message indicating that Linux does not recognize the command. Explain what the problem is. 

Linux is case-sensitive at the command line, and this command should be run in all lower case. Therefore, re-enter the command as follows: ifconfig eth0 down. That should release the DHCP lease. Once that is successful, you should renew the lease with the following command: sudoifconfig eth0 up

115. (p. 172) You need to renew the DHCP lease on an Apple Macintosh OS X client computer. Explain where in the GUI would you do this, and how you would initiate the renewal of the lease. 

To renew a DHCP lease on an Apple Macintosh OS X client computer, I would open System Preferences and select the Network utility. In Network, I would first ensure that the Configure IPv4 field was set to Using DHCP, and then I would click the button labeled Renew DHCP Lease.

116. (p. 148) Describe the TCP protocol. 

Used by most Application layer protocols, the TCP protocol uses segments as its PDU. It is connection-oriented, and uses ports, sequence numbers, flags, and acknowledgements to ensure that a communications session is established and functioning.

117. (p. 148-149) Describe the UDP protocol. 

It is a connectionless protocol that works at the Transport layer of the TCP/IP protocol suite. It does not concern itself with establishing a connection, error checking, or data sequencing. Its PDU is called a datagram.

118. (p. 146) What is the process called that changes data as it flows up and down the layers of the TCP/IP model called, and how does it work? 

It is called encapsulation. Each layer has a different PDU, and each layer below encapsulates the layer above with additional headers (and sometimes footers) and data from above. A packet's payload, for example, can be a TCP segment that consists of data from layers above and a sequence number.

119. (p. 149) List the fields in a UDP header. 

Source port, destination port, length, and checksum.

120. (p. 146-147) List two Internet layer protocols. 

The Internet Protocol (IP) and the Internet Control Message Protocol (ICMP).