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Cisco Bug: CSCue87407 - DNS: Inspection drops non in-addr.arpa PTR queries

Last Modified

Aug 08, 2018

Products (1)

  • Cisco ASA 5500-X Series Firewalls

Known Affected Releases

9.0(2) 9.1(1) 9.1(2)

Description (partial)

Symptom:
Non 'in-addr.arpa' PTR queries through an ASA firewall configured for DNS inspection will be dropped. For example a PTR query for IP 203.0.113.100 normally looks like 100.113.0.203.in-addr.arpa and this will be allowed by the inspection. However, if the query does not end with 'in-addr.arpa', the query will be dropped. An example of this would be 100.113.0.203.cisco.com .

Conditions:
This is seen on ASA code version 9.0.x and 9.1.x due to the introduction of the DNS 4-to-6 functionality in the DNS inspection engine.
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Bug Details Include

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