Chapter 30. Network Name ResolutionSOME OF THE MAIN TOPICS IN THIS CHAPTER ARE
Computers use hardware addresses when exchanging data on the local subnet. These addresses are burned into the network adapter and are often referred to as MAC (Media Access Control) addresses. MAC addresses produce a flat address space, so network protocols, such as IP, are typically used to create a hierarchical address space. However, for humans , both MAC and IP addresses (or IPX/SPX addresses, for that matter) are difficult to remember. Names are convenient for use by humans who have to operate computers. So, besides identifying a computer or network device using a protocol address, it's also important to be able to give a name to a computer, a network device, or a service, and then have that name resolved to the address so that data communications can take place on the network. Understanding how name resolution works on your network will better prepare you to troubleshoot the problems users encounter when trying to locate resources. This chapter deals with standard name resolution techniques ranging from the simple LMHOSTS files to the Windows Internet Name Service (WINS) for NetBIOS names and HOSTS files and the Domain Name System (DNS) service for IP names. For most networks, such as those that have Unix, Linux, or Windows computers, the name resolution methods described in this chapter will suffice. However, Windows 2000, Windows XP, or Windows Server 2003 ”when deployed using the Active Directory ”adds a whole new dimension to name resolution. The Active Directory stores objects that can represent everything from a user account to a resource on the network, such as a computer or a printer. In a similar fashion, Novell Directory Service ”NDS, now called the eDirectory ”is a directory-based solution for locating resources on the network. If you employ Windows 2000 Servers in your network, you might find the next chapter, "Using the Active Directory," to be an important resource. If your network is NetWare-based, Chapter 33, "Overview of the Novell Bindery and Novell Directory Services," and Chapter 34, "Expanding and Enhancing NDS: NetWare's eDirectory," will provide more detailed coverage of these technologies.
For Unix/Linux systems, the upgrade path from the older HOSTS file was Sun's Network Information System (NIS), which was formerly called Yellow Pages, until trademark issues forced a name change. Therefore, you'll find both NIS commands as well as commands that start with the letters yp on some Unix systems. Today there is a growing movement to move authentication and other information to an LDAP-based directory server. A number of LDAP-enabled directory servers can be used with different operating system platforms, and a quick search on the Internet can reveal a lot of information. In addition, there's an open source version of an LDAP server that you can review at http://www.openldap.org. For a basic overview of LDAP, see Appendix D, "The Lightweight Directory Access Protocol." When working in a multiprotocol environment, there are several ways in which you can create a single namespace using an LDAP-enabled directory to provide a single directory service for Windows, Unix, Linux, and NetWare clients . You'll find a discussion of these topics and the utilities that can help you get there in Part XI, "Migration and Integration," later in this book. |