WKS (well-known services) resource record

WKS records describe the well-known services supported by a particular protocol at a specified address. The list of services and port numbers comes from the list of services specified in /etc/services. There should be only one WKS record per protocol per address.

Because the WKS record is not widely used throughout the Internet, applications should not rely on the existence of this record to determine the presence or absence of a service. Instead, the application should simply attempt to use the service.

Here is an example of a WKS record:

   {name} {ttl} addr-class  WKS  address       protocol  list of services
                  IN        WKS  10.0.118.1  UDP         echo tftp time
                  IN        WKS  10.0.118.1  TCP         (telnet discard
                                                         sunrpc sftp
                                                         uucp-path systat 
                                                         netstat qotd nntp
                                                         link chargen ftp 
                                                         auth whois mtp
                                                         pop rje finger smtp
                                                         supdup hostnames 
                                                         domain
                                                         name server)