Microsoft Windows XP Professional Resource Kit 2003
ISBN: N/A
EAN: N/A
EAN: N/A
Year: 2005
Pages: 338
Pages: 338
In Windows XP Professional TCP/IP, 32 bit addresses are used to identify each node in the network. This means that every interface on every device has its own address. There are two types of authorized addresses: public authorized addresses and private authorized addresses. Unauthorized addresses can also be used. Four different methods can be used to assign IP addresses. Additionally, several methods exist for resolving device names to IP addresses.
In order to communicate on a private network or the Internet, each computer on a TCP/IP network must be identified by a unique 32 bit IP address. Public IP addresses and authorized private IP addresses on the Internet are assigned and managed by the Internet Assigned Numbers Authority (IANA). It is also possible, although not always advisable, to assign an unauthorized private address (that is, an address of your own choosing.)
In order for a computer to be visible on the Internet, it must be reachable through a public IP address. The IANA assigns ranges of public IP addresses to organizations that can then assign IP addresses within those ranges to individual computers. This prevents multiple computers from having the same IP address.
The public IP address for your Windows XP Professional based computer can either be assigned through a Dynamic Host Configuration Protocol (DHCP) server available in your enterprise network, configured manually, or provided by an Internet service provider (ISP) through a dial-up connection.
The IANA has reserved a certain number of IP addresses that are never used on the global Internet. These private IP addresses are used for networks that do not want to directly connect to the Internet, but nevertheless require IP connectivity. For example, a user wanting to connect multiple Windows XP Professional based computers in a home network can use the Automatic Private IP Addressing (APIPA) feature to allow each computer to automatically assign itself a private IP address. The user does not need to configure an IP address for each computer, nor is a DHCP server needed. For more information about APIPA, see Types of IP Address Assignment later in this chapter.
Computers on a network using authorized private IP addressing can connect to the Internet through the use of another computer with either proxy or network address translator (NAT) capabilities. Windows XP Professional includes the Internet Connection Sharing (ICS) feature that provides NAT services to clients in a private network. For more information about Internet Connection Sharing, see Connecting Remote Offices in this book.
It is possible, when there is an absolute certainty that your network will never access the Internet, to assign to a node a 32-bit unauthorized private IP address of your choosing. Keep in mind that if any Internet connectivity is ever established with any node on your network, these unauthorized private IP addresses could generate significant problems that would require you to immediately change the IP address of every node that you had assigned in this manner.
Windows XP Professional provides four methods for assigning IP addresses to TCP/IP clients:
Dynamic Host Configuration Protocol (DHCP). Provides automatic configuration of IP addresses and other configuration options (auto-configuration) for clients in a network with one or more DHCP servers. This is the default addressing method in Windows XP Professional.
Automatic Private IP Addressing (APIPA). Automatically assigns a private IP address to clients in a single-subnet environment where no DHCP server is available. When communicating within their own subnet, computers using APIPA addresses can communicate only with other computers using APIPA addresses. For more information about APIPA, see Enabling IP Address Assignment later in this chapter.
Static IP Addressing. Allows you to manually configure the IP address if DHCP and APIPA are not available or are not feasible. This method can be time-consuming and prone to error, especially on larger networks.
Alternate IP Configuration. Allows a single interface to make use of more than one IP address as long as only one is used at a time. New in Windows XP Professional, Alternate IP Configuration allows the user to configure a Windows XP Professional based computer to use one address (either a specified static address or an automatically configured one) and then if that attempt is not successful, to make another pre-configured attempt.
For more information about choosing a method for IP address assignment that best meets the needs of your environment, see Choosing an IP Address Assignment Method later in this chapter.
In general, users prefer to use computer names instead of IP addresses. In Windows XP Professional, TCP/IP allows a computer to communicate over a network with another computer by using a host name or a NetBIOS name in place of an IP address. The mechanisms for name resolution that Microsoft Windows supports include:
Domain Name System (DNS). A global, distributed database based on a hierarchical naming system. The hierarchical naming structure of DNS complements the hierarchical planning structure implemented in the Active Directory directory service, and is used as its naming service. DNS name resolution is used on the Internet to map friendly names to IP addresses, and vice versa. In Microsoft Windows 2000 and Microsoft Windows XP environments, DNS is the default name resolution method.
NetBIOS over TCP/IP (NetBT). Provides name resolution and connection services for clients using Microsoft Windows 95, Microsoft Windows 98, and Microsoft Windows Millennium Edition (Windows Me) operating systems, applications, and services. Microsoft Windows 2000 Server includes a NetBIOS name server known as the Windows Internet Name Service (WINS). NetBIOS over TCP/IP(NetBT) name resolution can take the form of any of four standard name-resolution node types defined in RFCs 1001 and 1002, as well as a fifth node type unique to the Windows implementation of IP name resolution. For more information about these node types, see Configuring NetBIOS Name Resolution later in this chapter.
When one computer attempts to communicate with another computer using one of these mechanisms for name resolution, the device name must be resolved to an IP address and ultimately to a hardware address.