Directory Service
- Last Updated on Wednesday, 06July , 2022 23:30 Written byScavenging
feature in DNS is one of the tricky features of DNS console. Although it is quite easy to understand the concepts
and configuration of scavenging
feature, I have seen many cases where stale records
are not being
scavenged due to a misconfiguration.
In order to
scavenge your records automatically, you must prepare the environment and configure the appropriate
settings. These settings reside in
both DNS and DHCP console. Firstly you need to make sure that you have configured the DHCP lease time properly. The
default value for DHCP lease time is
8 days. You can configure it to your desired
value but you need to keep this in mind that when you are configuring the DHCP lease time, you must
configure the Refresh- interval and
Non_Refresh interval based on the value of DHCP lease time. Let’s clarify
this with an example.
Suppose that I
have 12 days configured for my DHCP lease time, In that case if I seek to have scavenging configured properly, the sum
of the Refresh Interval and No-Refresh
Interval must be equal or less that DHCP lease time. Following configuration is a sample configuration:
DHCP
lease time: 12 days
No Refresh Interval: 6 days Refresh
Interval : 6 days
After that make
sure that the DHCP is properly configure to update DNS records in your DNS server. Something to keep in mind is that
when you have Integrated Zones there
is no need to configure DNS scavenging on ALL
the domain controllers. You only enable on one of your servers and automatically all the stale records will
be deleted. Thanks to our friend replication.
So far we have
configured the scavenging but it is not done yet! Yes, although you have enabled the DNS scavenging in one of your
domain controllers, it is not enabled
yet! Microsoft should have presented a separate
tab or menu in order to configure all the settings related to DNS scavenging but unfortunately they
must work on this aspect otherwise
people will be lost messing around to find a single configuration. Anyways, for the final part enable the feature
and wait for the scavenge period.
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