resolver.4 (2010 09)

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resolver(4) resolver(4)

NAME

resolver, resolv.conf - 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

determined from the local host name returned by gethostname()

(see gethost-

name(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.

retrans Retransmission timeout. It is interpreted during the

res_init() (see

resolver (3N)) call. It has higher precedence than setting it through the

set_resfeild() (see resolver (3N)) API and lower precedence than setting it

through the RES_RETRANS (see resolver (3N)) environment variable. Whenever an

invalid value is speciﬁed for retrans, a message is ﬂagged in syslog

. The

default value is 5000 milliseconds.

To use the

retrans option, add the following name-value pair in

/etc/resolv.conf:

retrans value-in-milliseconds

Example: To set the retransmission value to 6000, use:

retrans 6000

retry Number of retries. This is interpreted during the res_init() (see resolver (3N))

call. It has higher precedence than setting it through the set_resfeild() (see

resolver (3N)) API and lower precedence than setting it through the RES_RETRY

(see resolver (3N)) environment variable. Whenever an invalid value is speciﬁed for

retry, a message is ﬂagged in syslog. The default value is 4.

To use the

retry option, add the following name-value pair in

/etc/resolv.conf:

retry number-of-retries

Example: To set the number of retries to 6, use:

retry 6

search Search list for host-name lookup. If the search option is not used the search list will

contain only 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 com-

ponent 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

HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1

Summary of content (4 pages)

PAGE 1
resolver(4) resolver(4) NAME resolver, resolv.conf - 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.
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resolver(4) resolver(4) domains are not local, and that queries time out if no server is available for 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(3N) to be sorted in accordance with network numbers specified in the address list.
PAGE 3
resolver(4) resolver(4) recommends that the possible domains for the search list be limited to those domains administered within your trusted organization. For more information on the security implications of search lists please see RFC 1535. AUTHOR resolver was developed by the University of California, Berkeley. FILES /etc/resolv.conf Resolver configuration file. SEE ALSO named(1M), resolver(3N), gethostent(3N), hostname(5), RFC 1535.
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(Notes) A (Notes) rA 4 Hewlett-Packard Company −1− HP-UX 11i Version 3: September 2010