hosts

 

---

 
 
 
 File Formats                                             hosts(4)
 
 
 


NAME
      hosts - host name database
 


SYNOPSIS
      /etc/inet/hosts"
 
      /etc/hosts"
 


DESCRIPTION
      The hosts file is a local database that associates the names
      of  hosts  with  their Internet Protocol (IP) addresses. The
      hosts file can be used in conjunction with, or  instead  of,
      other  hosts  databases,  including  the  Domain Name System
      (DNS), the NIS hosts map and the NIS+ hosts table.  Programs
      use  library  interfaces  to access information in the hosts
      file.
 
      The hosts file has one entry for each  IP  address  of  each
      host.  If  a host has more than one IP address, it will have
      one entry for each, on consecutive lines. The format of each
      line is:
 
      IP-address official-host-name nicknames...
 
      Items are separated by any number of SPACE and/or TAB  char-
      acters.  The  first item on a line is the host's IP address.
      The second entry is the  host's  official  name.  Subsequent
      entries  on the same line are alternative names for the same
      machine, or "nicknames." Nicknames are optional.
 
      For a host  with  more  than  one  IP  address,  consecutive
      entries  for these addresses may contain the same or differ-
      ing nicknames. Different nicknames are useful for  assigning
      distinct names to different addresses.
 
      A call to  gethostbyname(3NSL) returns a  hostent  structure
      containing  the  union  of  all addresses and nicknames from
      each line containing a matching official name or nickname.
 
      A `#' indicates the beginning of a comment; characters up to
      the  end  of  the  line are not interpreted by routines that
      search the file.
 
      Network addresses are written in the  conventional  "decimal
      dot"  notation  and  interpreted using the inet_addr routine
      from   the   Internet    address    manipulation    library,
      inet(3SOCKET).
 
      This interface supports host names as defined  in   Internet
      RFC 952 which states:
 
 
 
 
 
 SunOS 5.8           Last change: 21 Mar 1995                    1
 
 
 
 
 
 
 File Formats                                             hosts(4)
 
 
 
      A "name" (Net, Host, Gateway, or Domain  name)   is  a  text
      string  up  to 24 characters drawn  from the alphabet (A-Z),
      digits (0-9), minus sign (-), and  period  (.).   Note  that
      periods  are  only  allowed  when they serve to delimit com-
      ponents of "domain style names".  (See RFC 921, Domain  Name
      System  Implementation  Schedule, for background).  No blank
      or space characters are permitted  as part of  a  name.   No
      distinction is made between upper and lower case.  The first
      character must be an alpha character.   The  last  character
      must not be a minus sign or period.
 
      Although the interface accepts host  names  longer  than  24
      characters  for  the  host portion  (exclusive of the domain
      component), choosing names for  hosts that adhere to the  24
      character  restriction  will insure maximum interoperability
      on the Internet.
 
      A host which serves as a GATEWAY should have  "-GATEWAY"  or
      "-GW"  as  part  of  its  name.  Hosts which do not serve as
      Internet gateways should not  use "-GATEWAY"  and  "-GW"  as
      part  of  their  names.   A  host which is a TAC should have
      "-TAC" as the last part of its host name, if  it  is  a  DoD
      host.  Single character names or nicknames are not allowed.
 
      RFC 952 has been modified by RFC 1123 to relax the  restric-
      tion on the first character being a digit.
 
 EXAMPLES
      Example 1: Example of a Typical Line From the hosts File
 
      Here is a typical line from the hosts file:
 
      192.9.1.20        gaia                        # John Smith
 


SEE ALSO
      in.named(1M),      gethostbyname(3NSL),       inet(3SOCKET),
      nsswitch.conf(4), resolv.conf(4)
 


NOTES
      /etc/inet/hosts is the official  SVR4  name  of  the   hosts
      file.   The symbolic link  /etc/hosts exists for  BSD compa-
      tibility.
 
 
 
 
 
 
 
 
 
 
 
 
 
 SunOS 5.8           Last change: 21 Mar 1995                    2
 
 
 

---