ultrix man page for hosts

hosts(5)							File Formats Manual							  hosts(5)

Name
       hosts - host name file

Description
       The  file  is  an  ASCII file that contains information about the known hosts on the DARPA Internet.  For each host a single line should be
       present with the following information:

       Internet address
       Official host name
       Aliases

       Each name is separated from the next by a new line.  Items are separated by any number of blanks or tab	characters.   A  number  sign  (#)
       indicates the beginning of a comment; characters up to the end of the line are not interpreted by routines that search the file.  This file
       is normally created from the official host data base maintained at the Network Information Control Center (NIC), though local  changes  may
       be required to bring it up to date regarding unofficial aliases or unknown hosts.

       Host  addresses	are  specified	in  the  conventional  dot (.) notation using the inet_addr routine from the Internet address manipulation
       library, Host names can contain any printable character other than a field delimiter, newline, or comment character.

       The database may be distributed in a network by a naming service, such as Yellow Pages or BIND/Hesiod.  See the Guide to the  Yellow  Pages
       Service or the Guide to the BIND/Hesiod Service for setup information.

Files
See Also
       gethostent(3n)
       Guide to the BIND/Hesiod Service
       Guide to the Yellow Pages Service

																	  hosts(5)