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Cisco Bug: CSCue87407 - DNS: Inspection drops non 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)

Non '' PTR queries through an ASA firewall configured for DNS inspection will be dropped. For example a PTR query for IP normally looks like and this will be allowed by the inspection. However, if the query does not end with '', the query will be dropped. An example of this would be .

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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