HP-UX Reference (11i v1 00/12) - 4 File Formats (vol 8)
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STANDARD Printed by: Nora Chuang [nchuang] STANDARD
/build/1111/BRICK/man4/!!!intro.4
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r
resolver(4) resolver(4)
NAME
resolver - resolver configuration file
SYNOPSIS
/etc/resolv.conf
DESCRIPTION
The resolver is a set of routines in the C library (see resolver(3N)) that provide access to the Internet
Domain Name System. The resolver configuration file contains information that is read by the resolver
routines the first time they are invoked by a process. The file is designed to be human-readable, and con-
tains a list of keywords with values that provide various types of resolver information.
If the only name server to be queried is on the local machine, then this file is not always necessary. The
domain name could be determined from the host name (see hostname(1)), if it has been set as a fully
qualified domain name.
Recognized configuration options include:
nameserver Internet (IP) address, in dot notation, of a name server that the resolver should query.
Up to MAXNS (currently 3) name servers can be listed, one per keyword. If there are
multiple servers, the resolver library queries them in the order listed. If no
nameserver entries are present, the default is to use the name server on the local
machine. (The algorithm used is: Try a name server; if the query times out, try the
next and continue until all name servers have been tried, then repeat trying all the
name servers until a maximum number of retries have been made).
domain Local domain name. Most queries for names within this domain can use short names
relative to the local domain. If no domain entry is present, the domain is deter-
mined from the local host name returned by gethostname()
(see gethostname(2));
the domain part is interpreted as everything after the first dot (
.). Finally, if the host
name does not contain a domain part, the root domain is assumed.
search Search list for host-name lookup. If the search option is not used the search list will
contain only the the local domain name. The search list can be changed by listing the
desired domain search path following the
search keyword with spaces or tabs
separating the names. Most resolver queries will be attempted using each component
of the search path in turn until a match is found. Note that this process may be slow
and generates a lot of network traffic if the servers for the listed domains are not
local, and that queries time out if no server is availablefor one of the domains.
The search list is currently limited to six domains with a total of 256 characters.
The first domain in the search list must be the local domain for short names to work
properly in various files (such as .rhosts and inetd.sec)
sortlist Causes addresses returned by gethostbyname(3C) to be sorted in accordance with net-
work numbers specified in the address list. This option allows you to specify which
subnets and networks for gethostbyname() to prefer if it receives multiple
addresses as the result of a query from the domain nameserver. The syntax is
sortlist addresslist
A sortlist is specified by IP address netmask pairs. The netmask is optional and
defaults to the netmask of the net. The IP address and optional netmask pairs are
separated by slashes. Up to 10 pairs may be specified. The pairs are separated by
blank spaces.
The following sortlist directive sorts the address on 128.32.42 subnet,
sortlist 128.32.42.0/255.255.255.0
The argument after the slash is the subnet mask for the subnet in question. To prefer
an entire network, you can omit the slash and the subnet mask:
sortlist 128.32.0.0
gethostbyname()
sorts any addresses in a reply that match these arguments into
the order in which they appear in the sortlist, and appends those addresses that do
not match to the end.
Section 4−−240 − 1 − HP-UX Release 11i: December 2000
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