◆ If a computer runs the Windows 98, Me, 2000, 2003, or XP operating system, is configured to use DHCP and cannot locate a DHCP server, it can be assigned an IP address and subnet mask through APIPA (Automatic Private IP Addressing). This configuration allows the computer to communicate with other computers on the same subnet only. ◆ A socket is a logical address assigned to a specific process running on a host. It forms a virtual circuit between the processes on two networked hosts. The socket’s address represents a combination of the host’s IP address and the port number asso- ciated with a process. ◆ IPv6 (IP version 6) is the latest version of IP. Its addresses are composed of eight 16-bit fields and total 128 bits. The larger address size results in up to 2 96 available IP addresses. IPv6 provides several other benefits over IPv4, including a more effi- cient header, better overall security, better prioritization allowances, and automatic IP address configuration. IPv6 is not yet widely implemented. ◆ Every host is identified by a host name and belongs to a domain. A domain is a group of hosts that share a domain name and have part of their IP addresses in common. ◆ Every domain is identified by its domain name. Usually, a domain name is associated with a company or other type of organization, such as a university or military unit. Domain names must be reserved with an ICANN-approved domain registrar. ◆ DNS (Domain Name System) is a hierarchical way of tracking domain names and their addresses. The DNS database does not rely on one file or even one server, but rather is distributed over several key computers across the Internet to prevent cata- strophic failure if one or a few computers go down. ◆ Name servers (or DNS servers) contain databases of names and their associated IP addresses. If one name server cannot resolve the IP address, the query passes to a higher-level name server. Each name server manages a group of machines called a zone. DNS relies on the hierarchical zones to distribute naming information. ◆ When one host needs to communicate with another host, it must first find its name server. Large organizations often maintain a primary and a secondary name server to help ensure Internet connectivity. You need to specify a name server’s IP address in the TCP/IP properties of a workstation so that the workstation will know which machine to query when looking up a name. Some key TCP/IP Application layer protocols include Telnet (for logging into hosts), FTP and TFTP (for transferring files between hosts), NTP (for synchroniz- ing time between hosts), NNTP (for storage and distribution of newsgroup mes- sages), and PING (for sending echo requests and echo replies that can indicate whether a host is responding). ◆ IPX/SPX (Internetwork Packet Exchange/Sequenced Packet Exchange) was used by Novell for its early versions of the NetWare NOS. IPX/SPX is required for interop- erability with LANs running NetWare versions 3.2 and lower. IPX/SPX is a suite of protocols that reside at different layers of the OSI Model. The IPX protocol handles network addressing information, making IPX/SPX routable. 182 Chapter 4 NETWORK PROTOCOLS ◆ IPX addresses contain two parts: the network address and the node address. The network address must be an 8-bit hexadecimal address. The node address is equal to a device’s MAC address. ◆ NetBEUI is a protocol that consumes few network resources, provides error correc- tion, and requires little configuration. But it can support only 254 connections and does not allow for good security. Furthermore, because NetBEUI lacks a Network layer, it is not routable and therefore unsuitable for large networks. ◆ WINS (Windows Internet Naming Service) is a service used on Windows systems to map IP addresses to NetBIOS names. ◆ AppleTalk is the protocol suite originally used to interconnect Macintosh comput- ers. Today’s Macintosh computers can still communicate via AppleTalk, but use TCP/IP as their default protocol suite. Key Terms Address Resolution Protocol—See ARP. address resource record—A type of DNS data record that maps the IP address of an Inter- net-connected device to its domain name. alias—A nickname for a node’s host name. Aliases can be specified in a local host file. anycast address—A type of address specified in IPv6 that represents a group of interfaces, any one of which (and usually the first available of which) can accept a transmission. At this time, anycast addresses are not designed to be assigned to hosts, such as servers or workstations, but rather to routers. AppleTalk—The protocol suite used to interconnect Macintosh computers. Although AppleTalk was originally designed to support peer-to-peer networking among Macintoshes, it can now be routed between network segments and integrated with NetWare- or Microsoft- based networks. AppleTalk network number—A unique 16-bit number that identifies the network to which an AppleTalk node is connected. AppleTalk node ID—A unique 8-bit or 16-bit number that identifies a computer on an AppleTalk network. AppleTalk zone—A logically defined group of computers on an AppleTalk network. ARP (Address Resolution Protocol)—A core protocol in the TCP/IP suite that belongs in the Network layer of the OSI Model. ARP obtains the MAC (physical) address of a host, or node, and then creates a local database that maps the MAC address to the host’s IP (logical) address. ARP cache—See ARP table. Chapter 4 183 KEY TERMS ARP table—A database of records that map MAC addresses to IP addresses. The ARP table is stored on a computer’s hard disk where it is used by the ARP utility to supply the MAC addresses of network nodes, given their IP addresses. binding—The process of assigning one network component to work with another. BOOTP (Bootstrap Protocol)—An Application layer protocol in the TCP/IP suite that uses a central list of IP addresses and their associated devices’ MAC addresses to assign IP addresses to clients dynamically. BOOTP was the precursor to DHCP. Bootstrap Protocol—See BOOTP. DHCP (Dynamic Host Configuration Protocol)—An Application layer protocol in the TCP/IP suite that manages the dynamic distribution of IP addresses on a network. Using DHCP to assign IP addresses can nearly eliminate duplicate-addressing problems. diskless workstation—A workstation that doesn’t contain a hard disk, but instead relies on a small amount of read-only memory to connect to a network and to pick up its system files. DNS (Domain Name System or Domain Name Service)—A hierarchical way of tracking domain names and their addresses, devised in the mid-1980s. The DNS database does not rely on one file or even one server, but rather is distributed over several key computers across the Internet to prevent catastrophic failure if one or a few computers go down. DNS is a TCP/IP service that belongs to the Application layer of the OSI Model. domain name—The symbolic name that identifies a domain. Usually, a domain name is asso- ciated with a company or other type of organization, such as a university or military unit. Domain Name Service—See DNS. Domain Name System—See DNS. dotted decimal notation—The shorthand convention used to represent IP addresses and make them more easily readable by humans. In dotted decimal notation, a decimal number between 0 and 255 represents each binary octet. A period, or dot, separates each decimal. dynamic address—An IP address that is assigned to a device through DHCP and may change when the DHCP lease expires or is terminated. dynamic ARP table entry—A record in an ARP table that is created when a client makes an ARP request that cannot be satisfied by data already in the ARP table. Dynamic Host Configuration Protocol—See DHCP dynamic IP address—An IP address that is assigned to a device upon request and may change over time. BOOTP and DHCP are two ways of assigning dynamic IP addresses. Dynamic Ports—TCP/IP ports in the range of 49152 through 65535, which are open for use with- out requiring administrative privileges on a host or approval from IANA. echo reply—The response signal sent by a device after another device pings it. 184 Chapter 4 NETWORK PROTOCOLS echo request—The request for a response generated when one device pings another device. external network number—Another term for the network address portion of an IPX/SPX address. File Transfer Protocol—See FTP. Format Prefix—A variable-length field at the beginning of an IPv6 address that indicates what type of address it is (for example, unicast, anycast, or multicast). FTP (File Transfer Protocol)—An Application layer protocol used to send and receive files via TCP/IP. hop—A term used to describe each trip a unit of data takes from one connectivity device to another. Typically, “hop” is used in the context of router-to-router communications. host file—A text file that associates TCP/IP host names with IP addresses. host name—A symbolic name that describes a TCP/IP device. hosts—Name of the host file used on UNIX, Linux, and Windows systems. On a UNIX- or Linux-based computer, hosts is found in the /etc directory. On a Windows-based computer, it is found in the %systemroot%\system32\drivers\etc folder. ICMP (Internet Control Message Protocol)—A core protocol in the TCP/IP suite that noti- fies the sender that something has gone wrong in the transmission process and that packets were not delivered. IGMP (Internet Group Management Protocol or Internet Group Multicast Protocol)—A TCP/IP protocol used to manage multicast transmissions. Routers use IGMP to determine which nodes use IGMP to join or leave a multicast group. Internet Control Message Protocol—See ICMP. Internet Group Management Protocol—See IGMP. Internet Group Multicast Protocol—See IGMP. internetwork—To traverse more than one LAN segment and more than one type of network through a router. Internetwork Packet Exchange—See IPX. Internetwork Packet Exchange/Sequenced Packet Exchange—See IPX/SPX. IP datagram—The IP portion of a TCP/IP frame that acts as an envelope for data, holding information necessary for routers to transfer data between subnets. IP next generation—See IPv6. IPv4LL (IP version 4 Link Local)—A protocol that manages automatic address assignment among locally connected nodes. IPv4LL is part of the Zeroconf group of protocols. Chapter 4 185 KEY TERMS ifconfig—A TCP/IP configuration and management utility used with UNIX and Linux sys- tems. ipconfig—The utility used to display TCP/IP addressing and domain name information in the Windows NT, Windows 2000, and Windows XP operating systems. IPng—See IPv6. IPv4 (IP version 4)—The current standard for IP addressing that specifies 32-bit addresses composed of four octets. IPv6 (IP version 6)—A newer standard for IP addressing that will replace the current IPv4 (IP version 4). Most notably, IPv6 uses a newer, more efficient header in its packets and allows for 128-bit source and destination IP addresses.The use of longer addresses will allow for many more IP addresses to be in circulation. IPX (Internetwork Packet Exchange)—A core protocol of the IPX/SPX suite that operates at the Network layer of the OSI Model and provides routing and internetwork services, simi- lar to IP in the TCP/IP suite. IPX address—An address assigned to a device on an IPX/SPX-based network. IPX/SPX (Internetwork Packet Exchange/Sequenced Packet Exchange)—A protocol orig- inally developed by Xerox, then modified and adopted by Novell in the 1980s for the NetWare network operating system. label—A character string that represents a domain (either top-level, second-level, or third- level). lease—The agreement between a DHCP server and client on how long the client can use a DHCP-assigned IP address. DHCP services can be configured to provide lease terms equal to any amount of time. loopback address—An IP address reserved for communicating from a node to itself (used mostly for troubleshooting purposes). The loopback address is always cited as 127.0.0.1, although in fact, transmitting to any IP address whose first octet is “127” will contact the orig- inating device. loopback test—An attempt to contact one’s own machine for troubleshooting purposes. In TCP/IP-based networking, a loopback test can be performed by communicating with an IP address that begins with an octet of 127. Usually, this means pinging the address 127.0.0.1. multicast address—A type of address in the IPv6 that represents multiple interfaces, often on multiple nodes. An IPv6 multicast address begins with the following hexadecimal field: FF0x, where x is a character that identifies the address’s group scope. multicasting—A means of transmission in which one device sends data to a specific group of devices (not necessarily the entire network segment) in a point-to-multipoint fashion. Multicasting can be used for videoconferencing over the Internet, for example. multiprotocol network—A network that uses more than one protocol. 186 Chapter 4 NETWORK PROTOCOLS name server—A server that contains a database of TCP/IP host names and their associated IP addresses. A name server supplies a resolver with the requested information. If it cannot resolve the IP address, the query passes to a higher-level name server. name space—The database of Internet IP addresses and their associated names distributed over DNS name servers worldwide. net mask—See subnet mask. NetBEUI (NetBIOS Enhanced User Interface)—The Microsoft adaptation of the IBM Net- BIOS protocol. NetBEUI expands on NetBIOS by adding a Transport layer component. Net- BEUI is a fast and efficient protocol that consumes few network resources, provides excellent error correction, and requires little configuration. NetBIOS (Network Basic Input Output System)—A protocol designed by IBM to provide Transport and Session layer services for applications running on small, homogeneous networks. NetBIOS Enhanced User Interface—See NetBEUI. Network Basic Input Output System—See NetBIOS. network class—A classification for TCP/IP-based networks that pertains to the network’s potential size and is indicated by an IP address’s network ID and subnet mask. Network classes A, B, and C are commonly used by clients on LANs; network classes D and E are reserved for special purposes. network ID—The portion of an IP address common to all nodes on the same network or sub- net. Network News Transport Protocol—See NNTP. Network Time Protocol—See NTP. newsgroup—An Internet-based forum for exchanging messages on a particular topic. News- groups rely on NNTP for the collection and dissemination of messages. NNTP (Network News Transport Protocol)—An Application layer protocol in the TCP/IP suite which facilitates the exchange of newsgroup messages, or articles, between multiple servers and users. NTP (Network Time Protocol)—A simple Application layer protocol in the TCP/IP suite used to synchronize the clocks of computers on a network. NTP depends on UDP for Trans- port layer services. octet—One of the four 8-bit bytes that are separated by periods and together make up an IP address. Packet Internet Groper—See PING. ping—To send an echo request signal from one node on a TCP/IP-based network to another, using the PING utility. See also PING. Chapter 4 187 KEY TERMS PING (Packet Internet Groper)—A TCP/IP troubleshooting utility that can verify that TCP/IP is installed, bound to the NIC, configured correctly, and communicating with the network. PING uses ICMP to send echo request and echo reply messages that determine the validity of an IP address. port number—The address on a host where an application makes itself available to incoming data. RARP (Reverse Address Resolution Protocol)—A core protocol in the TCP/IP suite that belongs in the Network layer of the OSI Model. RARP relies on a RARP table to associate the IP (logical) address of a node with its MAC (physical) address. RARP can be used to sup- ply IP addresses to diskless workstations. Registered Ports—TCP/IP ports in the range of 1024 to 49151. These ports are accessible to network users and processes that do not have special administrative privileges. Default assign- ments of these ports must be registered with IANA. release—The act of terminating a DHCP lease. Rendezvous—Apple Computer’s implementation of the Zeroconf group of protocols. resolver—Any host on the Internet that needs to look up domain name information. resource record—The element of a DNS database stored on a name server that contains information about TCP/IP host names and their addresses. Reverse Address Resolution Protocol—See RARP. root server—A DNS server maintained by ICANN and IANA that is an authority on how to contact the top-level domains, such as those ending with .com, .edu, .net, .us, and so on. ICANN oversees the operation of 13 root servers around the world. routable—Protocols that can span more than one LAN because they carry Network layer and addressing information that can be interpreted by a router. Sequenced Packet Exchange—See SPX. socket—A logical address assigned to a specific process running on a computer. Some sockets are reserved for operating system functions. SPX (Sequenced Packet Exchange)—One of the core protocols in the IPX/SPX suite. SPX belongs to the Transport layer of the OSI Model and works in tandem with IPX to ensure that data are received whole, in sequence, and error free. static ARP table entry—A record in an ARP table that someone has manually entered using the ARP utility. Static ARP table entries remain the same until someone manually modifies them with the ARP utility. static IP address—An IP address that is manually assigned to a device and remains constant until it is manually changed. 188 Chapter 4 NETWORK PROTOCOLS subnet—A part of a network in which all nodes shares a network addressing component and a fixed amount of bandwidth. subnet mask—A 32-bit number that, when combined with a device’s IP address, indicates what kind of subnet the device belongs to. subnetting—The process of subdividing a single class of network into multiple, smaller net- works. subprotocols—Small, specialized protocols that work together and belong to a protocol suite. switch—The letters or words added to a command that allow you to customize a utility’s out- put. Switches are usually preceded by a hyphen or forward slash character. TCP (Transmission Control Protocol)—A core protocol of the TCP/IP suite. TCP belongs to the Transport layer and provides reliable data delivery services. TCP/IP (Transmission Control Protocol/Internet Protocol)—A suite of networking pro- tocols that includes TCP, IP, UDP, and many others. TCP/IP provides the foundation for data exchange across the Internet. TCP/IP core protocols—The major subprotocols of the TCP/IP suite, including IP,TCP, and UDP. Telnet—A terminal emulation protocol used to log on to remote hosts using the TCP/IP pro- tocol. Telnet resides in the Application layer of the OSI Model. TFTP (Trivial File Transfer Protocol)—A TCP/IP Application layer protocol that enables file transfers between computers. Unlike FTP,TFTP relies on UDP at the Transport layer and does not require a user to log on to the remote host. Time to Live—See TTL. TLD (top-level domain)—The highest-level category used to distinguish domain names— for example, .org, .com, .net. A TLD is also known as the domain suffix. top-level domain—See TLD. Transmission Control Protocol—See TCP. Transmission Control Protocol/Internet Protocol—See TCP/IP. Trivial File Transfer Protocol—See TFTP. TTL (Time to Live)—A number that indicates the maximum time that a datagram or packet can remain on the network before it is discarded. Although this field was originally meant to represent units of time, on modern networks it represents the number of router hops a data- gram has endured. The TTL for datagrams is variable and configurable, but is usually set at 32 or 64. Each time a datagram passes through a router, its TTL is reduced by 1. When a router receives a datagram with a TTL equal to 1, the router discards that datagram. Chapter 4 189 KEY TERMS UDP (User Datagram Protocol)—A core protocol in the TCP/IP suite that sits in the Trans- port layer of the OSI Model. UDP is a connectionless transport service. unicast address—A type of IPv6 address that represents a single interface on a device. An IPv6 unicast address begins with either FFC0 or FF80. User Datagram Protocol—See UDP. Well Known Ports—TCP/IP port numbers 0 to 1023, so named because they were long ago assigned by Internet authorities to popular services (for example, FTP and Telnet), and are therefore well known and frequently used. Windows Internet Naming Service—See WINS. WINS (Windows Internet Naming Service)—A service that resolves NetBIOS names with IP addresses. WINS is used exclusively with systems that use NetBIOS—therefore, it is found on Windows-based systems. Zeroconf (Zero Configuration)—A collection of protocols designed by the IETF to simplify the setup of nodes on a TCP/IP network. Zeroconf assigns a node an IP address, resolves the node’s host name and IP address without requiring a DNS server, and discovers services, such as print services, available to the node, also without requiring a DNS server. Review Questions 1. A _________________________ is a rule that governs how networks communicate. a. protocol b. subnet mask c. port d. namespace 2. _________________________ is a Network layer protocol that obtains the MAC address of a host, or node, then creates a database that maps the MAC address to the host’s IP address. a. Network Time Protocol b. File Transfer Protocol c. Address Resolution Protocol d. Internet Control Message Protocol 190 Chapter 4 NETWORK PROTOCOLS 3. _________________________ contain databases of associated names and IP addresses and provide this information to resolvers on request. a. Hosts b. IP datagrams c. Subnets d. Name servers 4. The _________________________ provides a means of resolving NetBIOS names to IP addresses. a. Dynamic Host Configuration Protocol b. Windows Internet Naming Service c. Network News Transport Protocol d. Internet Packet Exchange Protocol 5. _________________________ is the process of assigning one network component to work with another. a. Subnetting b. Multicasting c. Binding d. IP addressing 6. True or false? All protocols are routable. 7. True or false? TCP ensures reliable delivery through sequencing and checksums. 8. True or false? TCP is a connectionless transport device. 9. True or false? Every process on a machine is assigned a port number. 10. True or false? IPv6 addresses are composed of eight 16-bit fields and total 32 bits. 11. _________________________ allows one device to send data to a specific group of devices. 12. A(n) _________________________ is a special 32-bit number that, when combined with a device’s IP address, informs the rest of the network about the segment or net- work to which it is attached. Chapter 4 191 REVIEW QUESTIONS [...]... installing a PCMCIA-standard NIC is much easier than installing an expansion card NIC In general, you can simply turn off the machine, insert the card into the PCMCIA slot, as shown in Figure 5-11, then turn on the computer Most modern operating systems (such as Windows XP) allow you to insert and remove the PCMCIA-standard adapter without restarting the machine Make sure that the card is firmly inserted... the hardware installation, you can simply repeat the installation process for the first NIC, choosing a different slot The trick to using multiple NICs on one machine lies in correctly configuring the software for each NIC Simple NIC configuration is covered in the following section The precise steps involved in configuring NICs on servers will depend on the server’s networking operating system On... the desktop’s main menu, similar to the Start button in Windows XP 3 Point to System Settings, and then click Network The Network Configuration window opens, as shown in Figure 5-13 If a NIC is present and installed, it appears in the list of hardware devices in the Devices tab (and also on the Hardware tab) 1 FIGURE 5-13 Fedora Core Linux Network Configuration window 4 To begin adding drivers for... vary Read the NIC documentation carefully before installing the relevant drivers, and make sure you are installing the appropriate drivers Installing a device driver designed for Windows 95 on a Windows XP computer, for example, may cause problems To install NIC software from a Windows XP interface, you need access to the Windows XP software (via either a Windows XP CD or hard disk) and the device drivers... meaning of LED indicators vary from one manufacturer to another The following are some general guidelines, but the only way to know for certain what your NIC’s LEDs are trying to tell you is to read the documentation Your NIC may have one or more of the following lights, and they may or may not be labeled: ◆ ACT—If blinking, this LED indicates that the NIC is either transmitting or receiving data (in. .. sent with the NIC contains drivers for more than one type of NIC, you are asked to select the precise model you are using After making your choice, click OK.) 14 The wizard should find the appropriate driver for your NIC and install it onto your hard disk Later, it informs you that it has finished To continue, click Finish Close all open windows Procedures in this section work in most situations Because... able to install the proper drivers for your NIC automatically In that case, you can follow these steps to install NIC software on a client running Fedora Core, a Linux operating system packaged and distributed by Red Hat, Inc and the GNOME desktop (the default graphical user interface): Log in as root (the default administrator ID) or a user ID with equivalent privileges 2 Click the Main Menu icon in the... it (for example, in the case of a 100BASE-TX NIC deployed on a 10BASE-T network) ◆ TX—If blinking, this LED indicates that the NIC is functional and transmitting frames to the network ◆ RX—If blinking, this LED indicates that the NIC is functional and receiving frames from the network The next sections describe the variable settings you should understand when configuring NICs Depending on your computer’s... documentation and follow the installation instructions Some manufacturers supply setup programs that automatically install and register NIC software as soon as you run them, thereby eliminating the need to follow the steps outlined previously Installing NIC drivers on a UNIX or Linux workstation depends somewhat on the version you’re running For example, a recent version of Linux from Red Hat, which supports... Inefficiencies in mail delivery, such as letters being misdirected to the wrong transfer point, frustrate both the sender and the receiver of the mail and increase the overall cost of delivery I In data networks, the task of directing information efficiently to the correct destination is handled by hubs, routers, bridges, and switches In this chapter, you will learn about these devices and their roles in managing . used with UNIX and Linux sys- tems. ipconfig—The utility used to display TCP/IP addressing and domain name information in the Windows NT, Windows 2000, and Windows XP operating systems. IPng—See. known and frequently used. Windows Internet Naming Service—See WINS. WINS (Windows Internet Naming Service)—A service that resolves NetBIOS names with IP addresses. WINS is used exclusively with. Internet Groper—See PING. ping—To send an echo request signal from one node on a TCP/IP-based network to another, using the PING utility. See also PING. Chapter 4 187 KEY TERMS PING (Packet Internet