There are several options for specifying the client hostname in the exports data. Some options apply only when NODHCP is specified in the site attributes file and others apply regardless of the DHCP mode. The client specification options are as follows.

Single hostname

This is the most common format and the one supported in releases before z/OS V1R8. In this format the client is specified by a hostname recognized by the DNS resolver. This name must be unique and unchanging for the duration of the NFS connections. A client suffix may be specified with this format.

Netgroup name

Name of a netgroup defined in the local /etc/netgroup file. The group entry in the file lists the hosts who are members of the group. Only the host part of each netgroup member is considered for checking for membership. Empty host parts, or those containing a single dash (-) are ignored. Netgroup names must be preceded by an at-sign (@), for example @group. A client suffix may not be specified with this format.

Single IP address

A client may be specified by an IPv4 or IPv6 address. Invalid IPv4 or IPv6 address specifications are ignored. If the NFS server starts in IPv4 mode and an IPv6 address is specified, it is ignored. If the NFS Server starts in IPv6 mode and an IPv4 address is specified, the address is translated to an IPv4-mapped address (which is standard IPv4 address handling in IPv6 networks). This option is only valid in NODHCP mode. In DHCP mode such client specifications are ignored. A client suffix may be specified with this format.

IP networks

Directories can also be exported to all hosts on an IPv4 or IPv6 network or subnetwork simultaneously. For IPv4 networks, specify an IP address and netmask pair as address/netmask where the netmask can be specified in dotted-decimal format, or as a contiguous mask length. For example, either '/255.255.252.0' or '/22' appended to the network base address will result in identical subnetworks with 10 bits of hostname. IPv4 addresses and mask lengths are checked for format and range, and ignored if invalid. A range from 1 to 31 is assumed.

For IPv6 networks, this is done by specifying IPv6 address/prefix-length. For example, the node address 12AB:0:0:CD30:123:4567:89AB:CDEF and its subnet number 12AB:0:0:CD30::/60 can be abbreviated as 12AB:0:0:CD30:123:4567:89AB:CDEF/60. IPv6 addresses and prefix-length are checked for format and range, and ignored if invalid. A range from 1 to 127 is assumed.

If the NFS server starts in IPv4 mode and an IPv6 address is specified, it is ignored. If the NFS Server starts in IPv6 mode and an IPv4 address is specified, the address is translated to an IPv4-mapped address (standard IPv4 address handling in IPv6 networks).

This is option is only valid in NODHCP mode. In DHCP mode, IP network entries are ignored. A client suffix may not be specified with this format.