Name resolution using the Internet domain name system begins with the client-side resolver. The resolver is a set of routines that are built into the resolver library. The client resolver code is controlled by the following files:
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Files Controlling the Client Resolver Code |
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|
File |
Description |
/etc/resolv.conf |
Contains directives to specify the scope of a query |
/etc/nsswitch.conf |
Contains the reference to DNS for the hosts entry |
During the system identification phase of a Solaris 10 OS installation, you use several windows to configure the name service. You use function keys or the Escape key to continue through the different windows, depending on the type of installation. For this demonstration, the Escape keys are used. 
The installation window only allows the selection of DNS with the default of local files for the name service. Therefore, to use DNS with another name service, such as NIS or LDAP, you must manually modify the configuration files after the system is configured.
The instructions for editing the DNS client configuration files are as follows:
Editing the /etc/resolv.conf File
The /etc/resolv.conf file contains configuration directives for the DNS resolver. The directives include:
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Configuration Directives in the /etc/resolv.conf File |
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|
Directive |
Description |
nameserver |
Specifies the IP address of a name server for the DNS domain in which the host is located. You can list up to three name servers, one on each line. |
domain |
Specifies the local domain name. Specifying the local domain name allows queries using just the host name. |
search |
Provides a list of domain names, separated by spaces or tabs, that is appended to unqualified name queries until a match is found. When used without the presence of the domain directive, the first domain listed in the search list is the local domain. |
Domain and search are both valid directives used in the /etc/resolv.conf file, and if both appear together, the last directive listed is used.
The following resolv.conf example shows two name servers for the suned.sun.com domain. It also specifies two domain names, training.sun.com, and sun.com, to append to any requests received that are not fully qualified.
# cat /etc/resolv.conf nameserver 192.168.10.11 nameserver 192.168.20.88 domain suned.sun.com training.sun.com sun.com
Copying the /etc/nsswitch.dns File to the /etc/nsswitch.conf File
To configure a client to use DNS in combination with the system’s local files, copy the /etc/nsswitch.dns file to the /etc/nsswitch.conf file. This action only changes the hosts entry as follows:
# cat /etc/nsswitch.conf … hosts: files dns …
| Note: If you want to add DNS name resolution to a system currently running a name service, such as NIS or NIS+, you cannot copy a nsswitch template into the nsswitch.conf file. You must manually edit the current nsswitch file, and place the dns keyword on the hosts line in the specific location, along with other keywords. |
The following example shows that DNS is queried after NIS and the /etc/hosts file.
# cat /etc/nsswitch.conf … hosts: files nis dns …
