Domain Name Service (DNS) is a system which translates the meaningful Hostnames and Domain Names into valid IP Addresses. A DNS Client or a Resolver is a host or a network device which queries the DNS servers for various resource records like the IP Address for a host like a Mail Server.

If you configure your Solaris Server as a DNS client then you need to add the DNS servers which the resolver on the server query for various DNS records in the file

/etc/resolv.conf

The following is an example of a sample /etc/resolv.conf

$ cat /etc/resolv.conf

domain example.com
nameserver 10.10.10.1
nameserver 10.10.10.2
nameserver 10.10.10.3

search example.com example.co.uk example.net

where

domain – specifies the local domain. A search for a host in the domain can simply be done with the hostname without the Domain suffix.

nameserver – specifies the IP Address to it as a DNS server. There can be more than one DNS server specified by the nameserver keyword (one per line) listed in the file.

search – specifies a list of local domains to search for the hosts. This process is slow and generates a lot of traffic.

This is the most commonly found configuration on DNS clients or Resolvers. More advanced configurations include

sortlist – Sort the IP Addresses returned to the resolver
options -  Allows additional configurations to modify resolver variables.

For a detailed man page, click here

The NSCD daemon in Solaris and ofcourse in UNIX and most of the Linux falvors maintains the system cache including the DNS/Name service cache.

All it needs is to restart the nscd aemon to flush the DNS cache.

Do a

# ps -ef|grep nscd

This will find the PID for the NSCD daemon.

Now, do a

#pkill <PID>

#kill <PID>

Now, check if the nscd process is killed by using

# ps -ef|grep nscd

Now, start the nscd daemon by using

#/usr/sbin/nscd

 This should start the nscd daemon and there you go, you have flushed the DNS Cache in your Solaris Server.

Click here for the man page for NSCD in Solaris