Configuring the DNS Resolver

domain

Enter the default domain name. This string will be appended to queries passed to the local DNS server. The default names should be written without a trailing dot:

domain india.hp.com

It is important to get the syntax correct as the resolver does not report errors. If more than one instance of the domain keyword is present, the last instance will override. To specify multiple domains for an unqualified name lookup, use the search directive.

search

The search directive is optional but overrides the domain directive for specifying which domains should be searched for unqualified host name lookups. You should add a search entry if users on a system commonly try to connect to nodes in another domain. The format is the search directive followed by up to six domains, separated by a white space.

search cup.hp.com hp.com

nameserver

The nameserver directive tells the resolver the IP address of a name server to query. For example, the line:

nameserver 15.32.17.2

instructs the resolver to send queries to the name server running at IP address 15.32.17.2 instead of the local host.

The resolver will also allow you to specify up to three name servers using multiple nameserver directives. They will be tried in the order in which they appear in the RESLVCNF file, only passing to the next listed nameserver if the previous one is not responding. Note that the resolver will only query subsequent name servers if there is no response, if the previous nameserver has already replied that it cannot resolve a query, no further lookup will be attempted.

NOTE: It is very important that you omit the leading zeros in the domain name resolver files. If you enter leading zeros here, the resolver routines will interpret the numbers as octal numbers.

sortlist

This directive is a mechanism which lets you specify subnets and networks for the resolver to prefer if it receives multiple addresses as a result of a query. The format is the sortlist directive, followed by a list of network addresses may also include a subnet mask, which immediately follows the address, preceded by a slash symbol (/).

  sortlist 128.32.42.0/255.255.255.0 15.0.0.0

options

The options directive lets you set two internal resolver settings.

options debug

The above directive will set an internal flag which causes debugging information to be produced on standard output.

options ndots:2

The above directive sets the minimum number of dots a domain name query must contain before the resolver will assume that it is a fully qualified name and therefore does not need to append the default domain (or searchlist argument) before sending it to the server.

The options directive can combine both settings on the same line.

options debug ndots:2

lines

Beginning with a pound sign (#) or a semicolon (;) in the first column, they are interpreted as comments and ignored by the resolver.