Hello World!
We have a strange problem with a customer for which we provide secondary DNS services.
He uses a Microsoft DNS Server.
According to the RFC I found, the underscore character is only valid in SRV Records. In any other records, this is an invalid character.
Our Customers ADS Server keeps autocreating one records like this:
gc._msdcs.web.EXAMPLE.COM 1800 IN A 192.0.2.44
Bind refuses to accept zone transfers from his server and eventualy the zone expires on the secondary. Then the customer deletes the RR, the transfer is successfull, but shortly afterwards the mentioned A record with underscore is re-created by the ADS and the problem is back.
Is this some kind of MS DNS bug, or have the DNS RFCs been updated recently to also allow underscores in other RR and some non bleading edge versions of bind still use the check from previous rfc?
Benoit Panizzon
Am 30.08.2012 13:47, schrieb Benoit Panizzon:
Is this some kind of MS DNS bug, or have the DNS RFCs been updated recently to also allow underscores in other RR and some non bleading edge versions of bind still use the check from previous rfc?
well this is technically an invalid name...
check named.conf options check-names (f.e. check-names master warn)
hth
Hello Benoit
Our Customers ADS Server keeps autocreating one records like this: gc._msdcs.web.EXAMPLE.COM 1800 IN A 192.0.2.44
Which is kinda expected for an Active Directory DNS Zone. In fact what you see here is actually a glue record for the whole AD-part, as the _msdcs-part, which contains all the super duper secret special sauce of Active Directory, is a sub-zone within the named ad-zone.
So basically your customer made the error to use a real-world zone name (EXAMPLE.COM) as his AD-Name instead of EXAMPLE.LOCAL which would stay internal and have another, non ad-zone configured for the external domain.
It all comes down to the point that you should never try to use BIND as a secondary DNS of an AD-Zone as Microsoft apparently violate the RFCs as you already pointed out.
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André Keller -
Benoit Panizzon -
Roman Hochuli