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tonitodux avatar image
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tonitodux asked tonitodux answered

DNS entries duplicate entries, what settings for non-refresh and refersh interval?

Hi,

We have a 3.0 Subnet which is our VPN subnet governed by Cisco ASA. The subnet is ofcourse entered in the DNS manager, but we are not happy with the refresh interval. As it can be seen from the screenshot, we have duplicate IP addresses which are a big concern when using Veeam as backup for clients.
At the time of writing this question the date is 09.05.22 just for reference.

200143-dns.jpg


DHCP is all normal and does not hand out any duplicate IPs:

200125-dhcp.jpg


DHCP settings:
Lease duration for DHCP clients for 3.0 subnet limited to 7 days.
Name protection is not enabled

200126-dhcp-dns-settings.jpg


DNS settings for whole domain:
200144-dns-settings-01.jpg
200093-dns-settings-02.jpg

My question: What would be the best/safest scavenging settings and where do I set them exactly?

Any other suggestions? The Cisco ASA is working normally and has been checked by our network guy.

Cheers





windows-dhcp-dns
dns.jpg (89.9 KiB)
dhcp.jpg (52.5 KiB)
dns-settings-01.jpg (31.1 KiB)
dns-settings-02.jpg (61.5 KiB)
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KarlieWeng-MSFT avatar image
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KarlieWeng-MSFT answered

Hello @tonitodux tonitodux

You could refer to this article How DNS Aging and Scavenging Actually Work to set your non-refresh /refresh, and scavenging period.

NOTE: The windows DNS Client service renews DNS registration of client resource records every 24 hours.



Best Regards
Karlie


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tonitodux avatar image
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tonitodux answered

Sooooo, couple of months later. Microsoft premier support could not find anything wrong with our 2 DCs, one physical one virtual.
When I shutdown the virtual DC - the problem is gone! There are no more duplicate entries on the 3.0 subnet.
They had both running the DHCP Role. Three days ago I uninstalled the DHCP role from the DC VM and the problem is still present so that leaves us with the conclusion that the DNSes are having somekind of a "misfire". I will completely demote the DC VM and create a new one without the DHCP role, just AD and dns.

Cheers!

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