The resolver file (RESLVCNF.NET.SYS) is an initialization file for the
domain name resolver. It contains information needed by the network to
determine how to resolve a domain name to an IP address. This file is read by
the resolver routines the first time they are invoked by a process.
To create the resolver file, perform the following steps:
Copy the sample file, RSLVSAMP.NET.SYS, to
RESLVCNF.NET.SYS.
Modify RESLVCNF.NET.SYS using any ASCII editor so that it
contains information about the name servers, domain, and search order
for your network. The keywords included in the file are described
under "Fields."
To modify an already existing RESLVCNF.NET.SYS file, simply use your
editor to update and save the existing file.
Fields
Each entry in the resolver file consists of a keyword followed by a value
separated by white space. The keyword and its associated value must appear on a
single line and the keyword must start the line.
Figure 12-1 "Sample Resolver Configuration
File" shows an example of a resolver file. Comment lines start with a pound
sign (#).
domain
Enter the local domain name. Most queries for names within this domain
can use short names relative to the local domain name. If the host name
does not contain a domain part, the root domain is assumed. If more than
one instance of the domain keyword is present, the last instance
will override.
The domain name is composed of labels, with each label separated by a
period. Each label must start with a letter or digit, and have as
interior characters only letters, digits, hyphens (-), or underbars (_).
A domain name may have any number of labels, but its total length,
including periods, is limited to 255 characters.
label[.label][...]
Domain names are not case sensitive.
search
The search entry is optional and indicates the order in which
domains should be searched for host name lookup. You should add a
search entry if users on this system commonly try to connect to
nodes in other domains. The search list is limited to six domains with a
total of 256 characters. If more than one instance of the search
keyword is present, the last instance will override.
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 will generate a lot of network traffic if the servers for the listed
domains are not local. Note also that queries will time out if no server
is available for one of the domains.
nameserver
Enter the IP address of a name server the resolver should query. The
address must be in dot format, with leading zeros omitted and a period
between each grouping. See example addresses in
Figure 12-1 "Sample Resolver
Configuration File".
NOTE: It is very important that you omit the leading zeros in the
network addresses that you enter in the domain name resolver files. If you
enter leading zeros here, the domain name resolver will interpret the numbers
as octal numbers.
You can list up to three name servers, but you must use a separate keyword
entry for each. If there are multiple servers, the resolver will query them in
the order listed. If no nameserver entries are present, the default is
to use the HOSTS.NET.SYS file.
If you have no server, do not add any nameserver entries; the resolver
will immediately revert to the HOSTS.NET.SYS file.
Errors in the resolver file will be silently ignored by the resolver routines.
Figure 12-1 Sample Resolver Configuration File