Rogue DNS Settings appearing after initial DHCP lease

I am having issues with DNS settings changing on clients soon after allocation via DHCP. This is a workgroup only, no windows domain. DHCP is running from a Fortigate 60b which acts as the primary DNS server and Google DNS configured as secondary. The DHCP lease time is 8 days, these DNS changes can happen 3 times or more in a working day. The network consists of a single subnet, there is also an internal wireless network using Ubiquiti AP's.
1. Malware has been ruled out, having scanned machines with AV and Malware detection finding nothing.2. Have setup port mirroring on switch ports and scanned traffic for other sources of DHCP offer packets.. none found.3. When the DNS settings change they are different on each machine, but each time it is a valid IP for the network that can be found in the DHCP leases on the 60b.I was expecting to...
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I have AD integrated DNS server. Need advise how to set DNS aging\scavenging based on DHCP lease time. I know how the process works. Found couple of articles where is written "DHCP
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Please click on Propose As Answer or to mark this post as
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seryanhoj wrote:
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Hi all,
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Hello,
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IT-Beratung Rudolf Thilo
Schweinfurter Str. 131
97464 Niederwerrn
t: +49 (0)9721/6464840
f: +49 (0)9721/6464841
m: +49(0)171/685 9 685

Hello Craig,
thanks for your answer.
[VPN Client sometimes doesn't restore DNS settings after disconnecting]
e.g. TID 10096552 is telling such a trouble, that should be fixed with
BM VPN Client 3.8.10
> > Any suggestions appreciated,
> >
> This one seems to be so related to the design of the VPN client that
> you may need to open an incident to get it fixed, if that even would
> help.
>
> There used to be a utility designed to clean up after the VPN client,
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> remember.
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Scenario
VPN connect
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any problems.
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missbehaviour when VPN connects are not disconnected clean. IIRC this
was something fixed in a VPN client version /several/ subversions ago)
Home Office PC = XPSP2+Hotfixes, VPN Client BM 3.8.16, nici from that
one first, now taken from NWClient 4.91.4, no difference.
Regards, Rudi.
IT-Beratung Rudolf Thilo
Schweinfurter Str. 131
97464 Niederwerrn
t: +49 (0)9721/6464840
f: +49 (0)9721/6464841
m: +49(0)171/685 9 685

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Rogue DNS Settings appearing after initial DHCP lease

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