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6 Appendix: Configuring DNS Servers In the examples below, we set up an SRV record to handle H.323 URIs of the form
user@example.com. These are handled by the Gatekeeper with the fully qualified domain
name of Gatekeeper1.example.com which is listening on port 1719, the default registration
port.
It is assumed that an A record already exists for Gatekeeper1.example.com. If not, you will
need to add one.
6.1 Microsoft DNS Server It is possible to add the SRV record using either the command line or the MMC snap in. To
use the command line: on the DNS server open a command window and enter
dnscmd . /RecordAdd domain service_name SRV service_data
Where domain is the domain into which you wish to insert the record, service_name the
name of the service you’re adding and service_data the priority, weight, port and server
providing the service as defined by RFC 2782. For example:
dnscmd . /RecordAdd example.com _h323ls._udp SRV \
1 0 1719 gatekeeper1.example.com
6.2 BIND 8 & 9 BIND is a commonly used DNS server on UNIX and Linux systems. Configuration is based
around two sets of text files: named.conf which describes which zones are represented by the
server and a selection of zone files which describe the detail of each zone.
BIND is sometimes run chrooted for increased security. This gives the program a new root
directory, which means that the configuration files may not appear where you expect them to
be. To see if this is the case on your system, run
ps aux | grep ^named
This will give the command line that named (the BIND server) was invoked with. If there is a
–t option, then the path following that is the new root directory and your files will be located
relative to that root.
In /etc/named.conf look for a directory entry within the options section. This will
give the directory in which the zone files are stored, possibly relative to a new root directory.
In the appropriate zone section, a file entry will give the name of the file containing the
zone details.
1. Edit the appropriate zone file for the domain example.com
2. Add an entry:
_h323ls._udp SRV 1 0 1719 gatekeeper1
Be careful not to end either service or target with a period (.) as this will prevent BIND
adding the domain to the end of the partial name.
3. Reload the configuration files. To do this find the process id (pid) for named
ps aux | grep ^named