Domain Name System

E - Mail

DOMAIN NAME SYSTEM

START AD SERVICES VLANS LDAP PPP TCP/IP WIN2000 FRAMES

VPN DNS TECH HI TECH DSL NETMAN OSI SWITCH DDNS

Web Links

William Mohawk

P.O. Box 1612

Santa Monica, CA 90406

The Internet Protocol addresses is a 32- bit integer. If somebody wants to send a message it is necessary to include the destination address, but people prefer to assign machines pronounceable, easily remembered names (host names). For this reason the Domain Name System is used. These logical names also allow independence from knowing the physical location of a host. A host may be moved to a different network, while the users continue to use the same logical name.

The Domain Name System (DNS) is a distributed database used by TCP/IP applications to map between hostnames and IP addresses, and to provide electronic mail routing information. Each site (university department, campus, company, or department within a company, for example) maintains its own database of information and runs a server program that other systems across the Internet can query. The DNS provides the protocol which allows clients and servers to communicate with each other.

The domain name system uses a hierarchical naming scheme known as domain names, which is similar to the Unix file system tree. The root of the DNS tree is a special node with a null label. The name of each node (except root) has to be up to 63 characters. The domain name of any node in the tree is the list of labels, starting at that node, working up to the root, using a period ("dot") to separate the labels (individual sections of a name might represent sites or a group, but the domain system simply calls each section a label ). The difference between the Unix file system and the tree of the DNS is that in the DNS we start on the ground and "go up" till the root. Writing them in this order makes it possible to compress messages that contain multiple domain names. Thus, the domain name "tau.ac.il" contains three labels: "tau", "ac", and "il". Any suffix of a label in a domain name is also called a domain. In the above example the lowest level domain is "tau.ac.il" (the domain name for the Tel-Aviv University Academic organization in Israel), the second level domain is "ac.il" (the domain name for Academic organizations of Israel), and the top level domain (for this name) is "il" (the domain name for Israel).

Web Links