The Host Table

The host table is a simple text file that associates IP addresses with host names. On NT systems, the table is in the file %SystemRoot%\System32\Drivers\etc\hosts. Each table entry in the hosts file contains an IP address separated by white space from a list of host names associated with that address. Comments begin with #.

The host table on the workstation pooh might contain the following entries:

#
# Table of IP addresses and host names
#
172.16.12.2 	pooh.ttgnet.com pooh
127.0.0.1 	localhost
172.16.12.1 	thoth.ttgnet.com thoth www
172.16.12.4 	wotan.ttgnet.com wotan
172.16.12.3 	kerby.ttgnet.com kerby
172.16.1.2 	kiwi.ttgnet.com kiwi
172.16.6.10 	thor.sales.ttgnet.com thor.sales thor

The first entry in the sample table is for pooh itself. The IP address 172.16.12.2 is associated with the host name pooh.ttgnet.com and the alternate host name (or alias) pooh. The host name and all of its aliases resolve to the same IP address, in this case 172.16.12.2.

Aliases provide for name changes, alternate spellings, and shorter host names. They also allow for generic host names. Look at the entry for 172.16.12.1. One of the aliases associated with that address is www. www is the generic name most users expect to find when searching for information via the Web. Other commonly used generic host names are ns for name servers, mailhost for mail servers, and news for network news servers.

The second entry in the sample file assigns the address 127.0.0.1 to the host name localhost. As we ...

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