*nix Documentation Project
·  Home
 +   man pages
·  Linux HOWTOs
·  FreeBSD Tips
·  *niX Forums

  man pages->IRIX man pages -> dns (7)              


DNS(7P)								       DNS(7P)

NAME    [Toc]    [Back]

     dns - Domain Name Service

SYNOPSIS    [Toc]    [Back]


DESCRIPTION    [Toc]    [Back]

     The Domain	Name System (DNS) is an	Internet standard name service for
     hostname to address translation.  Queries are made	from a client library
     (termed the resolver(4)) to a server daemon named(1M).  The daemon
     nsd(1M) will make these calls and present the data	in a filesystem
     namespace when the	dns keyword exists in the nsswitch.conf	configuration
     file for a	domain.	 This man page documents the behavior of the DNS
     extension to the nsd daemon.

     The nsd daemon reads all of the nsswitch.conf configuration files,	first
     /etc/nsswitch.conf	for the	default	domain,	then files
     /var/ns/domains/DOMAIN/nsswitch.conf for each DOMAIN the local host acts
     as	a server for.  As it reads these files if it encounters	the keyword
     dns for some map then it will open	the DNS	library
     /var/ns/lib/libns_dns.so.	On first open the library initialization
     routine will parse	the resolver configuration file	/etc/resolv.conf to
     determine the addresses of	nameservers and	the domain names to use	for

     Extended attributes in the	nsswitch.conf file can be used to control the
     behavior of the DNS resolver.  Extended attributes	are simply lists of
     key/value pairs attached to each object in	the nsd	filesystem.  The
     attributes	supported in this library are:

	  This is the domainname given as a parameter to the remote name
	  server.  This	attribute is typically inherited from the daemon
	  depending on the nsswitch.conf file that is being read.  Given the
	  configuration	file /var/ns/domains/DOMAINNAME/nsswitch.conf the
	  attribute "domain" is	set to DOMAINNAME.  For	the default domain,
	  represented by the file /etc/nsswitch.conf, the domain is unset and
	  the DNS library uses the search path given in	the resolver(4)
	  configuration	file.  If the resolv.conf file is changed then the
	  change will be reflected in the next lookup.

	  The table attribute is typically inherited from the daemon based on
	  the line from	which this entry occurs	in the nsswitch.conf file.
	  This implementation of the DNS resolver recognizes only two tables:
	  hosts.byname which is	translated into	a type A request, hosts.byaddr
	  which	is translated into a type PTR request.

     key  The key attribute is set by the daemon on each request.  If the
	  address is fully qualified (ends in a	'.') then it is	forwarded on
	  to the remote	name server as is.  Else, it will have each element of
	  the search path appended and looked up.  If the key contains a

									Page 1

DNS(7P)								       DNS(7P)

	  sufficient number of dots (as	defined	by in resolv.conf as "option
	  ndots") then it will first be	attempted as is.

	  The dns_max_ttl attribute specifies that nsd should use the DNS TTL
	  value	for the	nsd cache timeout.  Because DNS	TTL values can be
	  quite	large a	maximum	value in seconds can be	specified.  Default is
	  zero.	 dns_servers The dns_servers attribute is a space separated
	  list of IP addresses of DNS servers.	If this	is not set then	the
	  nameservers listed in	the /etc/resolv.conf file are used.

	  The dns_search attribute is used to override the default domain
	  search path built from /etc/resolv.conf.

	  The dns_parallel attribute is	a boolean which	specifies use of a
	  performance optimization where queries will be made to all defined
	  name servers in parallel.  This is only beneficial if	each of	the
	  name servers is equally able to answer the request. By default this
	  is 0.

	  The dns_retries attribute specifies the number of queries that we
	  will make to each server.  Each server is tried in turn in a roundrobin
	basis until the	number of retries is exhausted.	 This should
	  be set to an integer value, and defaults to 3.

	  The dns_timeout attribute is the number of milliseconds the library
	  code will wait for a response	from a name server before continuing
	  to the next name server.  The	default	is 2000.

NOTE    [Toc]    [Back]

     If	there is no resolv.conf	file on	a system nsd will NOT use a default
     nameserver	of localhost unless named has been enabled via chkconfig.

SEE ALSO    [Toc]    [Back]

     chkconfig(1M), named(1M), nsd(1M),	nsswitch.conf(4), resolver(4), db(7P),
     dns(7P), files(7P), ldap(7P), mdbm(7P), ndbm(7P), nis(7P),	nisserv(7P).
     IRIX Admin: Networking and	Mail

									PPPPaaaaggggeeee 2222
[ Back ]
 Similar pages
Name OS Title
getdomainna HP-UX get/set name of current Network Information Service domain
domainname HP-UX set or display name of Network Information Service domain
setdomainna HP-UX get/set name of current Network Information Service domain
whois FreeBSD Internet domain name and network number directory service
whois OpenBSD Internet domain name and network number directory service
bind_intro Tru64 Introduction to the Berkeley Internet Name Domain (BIND) service
bind_manual_setup Tru64 Describes how to manually set up the Berkeley Internet Name Domain (BIND) service on your network.
rpccp_remove_entry HP-UX Removes a name service entry from the name service database
rpccp_add_entry HP-UX Adds a name service entry to the name service database
getdomainname Linux get/set domain name
Copyright © 2004-2005 DeniX Solutions SRL
newsletter delivery service