D-Link NetDefendOS User Manual page 283

There is one exception to the default behaviour and that is after a reconfigure which is the
result of getting a new local IP address on the interface that connects to the DNS server.
In this case, NetDefendOS always waits a predefined period of 20 seconds before reposting
after the reconfiguration.
• The default Repost Delay is 1200 seconds (20 minutes). This can be altered.
The predefined DynDNS client has an predefined refetch time of 30 days which cannot be
changed.
The difference between HTTP Poster and the predefined named DNS servers is that HTTP Poster
can be used to send any URL. The named services are a convenience that make it easy to
correctly format the URL needed for that particular service. For example, the http:// URL for the
dyndns.org service might be:
myuid:mypwd@members.dyndns.org/nic/update?hostname=mydns.dyndns.org
This could be sent by using HTTP Poster. Alternatively, the URL could be automatically formatted
for the administrator by NetDefendOS through using the DynDNS option and entering only the
information required for dyndns.org.
The CLI console command httpposter can be used to troubleshoot problems by seeing what
NetDefendOS is sending and what the servers are returning:
gw-world:/> httpposter
Note: A high rate of server queries can cause problems
Dynamic DNS services are often sensitive to repeated login attempts over short periods
of time and may blacklist source IP addresses that are sending excessive requests. It is
therefore not advisable to query these servers too often, otherwise they may cease to
respond.
A repost for an individual server can be forced with the command:
gw-world:/> httpposter -repost=<index>
Where <index> is the position of the object in the list of posters. For example, to force a report of
the second in the list:
gw-world:/> httpposter -repost=2
HTTP Poster Has Other Uses
HTTP Poster may be used for other purposes than dynamic DNS. Any requirement for
NetDefendOS to send an HTTP GET or POST message to a particular URL could be met using this
feature.
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Chapter 3: Fundamentals