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21.6.4. Hostname Formats

The host(s) can be in the following forms:
  • Single machine — A fully qualified domain name (that can be resolved by the server), hostname (that can be resolved by the server), or an IP address.
  • Series of machines specified with wildcards — Use the * or ? character to specify a string match. Wildcards are not to be used with IP addresses; however, they may accidentally work if reverse DNS lookups fail. When specifying wildcards in fully qualified domain names, dots (.) are not included in the wildcard. For example, * includes but does not include
  • IP networks — Use a.b.c.d/z, where a.b.c.d is the network and z is the number of bits in the netmask (for example Another acceptable format is a.b.c.d/netmask, where a.b.c.d is the network and netmask is the netmask (for example,
  • Netgroups — In the format @group-name, where group-name is the NIS netgroup name.