12-16-2021 03:50 AM
Hi,
I have two ISE 3.0 (Patch 2) appliances. I ran an Active directory diagnostic check on ISE01 and there are three warnings which I need to look into.
Both appliances are failing on the same three items.
ISE-01 ISSUE 1:
ISE-01 =
Test Name :DNS A/AAAA record low level API query
Description :Query for DNS A/AAAA record using resolv.conf configuration and res_query()
Instance :AD_Domain
Status :Warning
Start Time :23:07:17 03.11.2021 GMT
End Time :23:07:17 03.11.2021 GMT
Duration :<1 sec
Result and Remedy...
Large DNS reply (1648 bytes) found in Address Record query response.
Large DNS replies can impact efficiency and usually indicate that ISE is not using a good Active Directory Site, or the DNS server response contains too many records.
ISE-01 ISSUE 2:
Test Name :DNS SRV record query
Description :Query for DNS SRV record using resolv.conf configuration and gethostbyaddr
Instance :AD_Domain
Status :Warning
Start Time :23:07:17 03.11.2021 GMT
End Time :23:07:17 03.11.2021 GMT
Duration :<1 sec
Result and Remedy...
SRV record found.
Not all SRV records have IP, will need to run additional query for get IP.
ISE-01 ISSUE 3:
Test Name :DNS SRV record size
Description :Query for DNS SRV record size using resolv.conf configuration and gethostbyaddr
Instance :AD_Domain
Status :Warning
Start Time :23:07:17 03.11.2021 GMT
End Time :23:07:17 03.11.2021 GMT
Duration :<1 sec
Result and Remedy...
SRV query size exceeds maximum limit of 4k. This may have negative impact on AD functionality. Check AD DNS configuration.
Can ISE determine the following:
what SRV records do not have IP,?
what SRV query size exceeds the max limit?
Are there any AD tools that I can run on the Domain Controllers to try and resolve these three issues? Should I add in the other DNS servers that the customer has (roughly 60-70 servers)?
Thanks
Anthony.
12-16-2021 01:25 PM
@Anthony O'Reilly - is the AD integration functioning ok though?
I wonder if these DNS related symptoms are due to IPv6 results returned in the DNS SRV query. Perhaps the DNS server is responding on its IPv6 interfaces too.
I agree with you - the ISE AD diagnostics are great but some more detail would be appreciated (in the tool itself) - because it raises concerns and then leaves the user guessing
12-19-2021 10:27 PM
Arne gave an example on a SRV query at his response for "ISE 3.0.0.458 - Error joining ISE to AD domain" .
I would suggest to take network packet captures between ISE and DNS servers while attempting these tests.
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