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Cisco Bug: CSCvs48735 - IOS-XE XE316, DNS feature behavioral change since XE316.

Last Modified

Dec 18, 2019

Products (1)

  • Cisco IOS

Known Affected Releases


Description (partial)

Starting from XE316, we replaced the legacy DNS stack in IOS with the open source Unbound DNS stack. 
There is no available documentation to track the changes. However from testing on the field here is the list of features that seems to have been changed :

- DNS retry and timeout could no longer be set for CLI (if the command still exists it is not working anymore )
- the "ip name-server" command does not choose the DNS servers in order like in IOS but uses a complex algorithm based on RTT/RTO.
- the "show ip dns server" command has been introduced.
- the "no ip domain-lookup" command will disable any other DNS resolution configured.

Starting from IOS-XE 3.16.x onward
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