Bug ID 911497: Unbound's backoff algorithm interacts badly with net resolver iRules

Last Modified: Apr 24, 2024

Affected Product(s):
BIG-IP TMOS(all modules)

Known Affected Versions:
15.1.0,,,,,, 15.1.1, 15.1.2,, 15.1.3,, 15.1.4,, 15.1.5,, 15.1.6,, 15.1.7, 15.1.8,,, 15.1.9,, 15.1.10,,,, 16.0.0,, 16.0.1,,, 16.1.0, 16.1.1, 16.1.2,,, 16.1.3,,,,,, 16.1.4,,,

Opened: May 22, 2020

Severity: 3-Major


Using RESOLVER::name_lookup in an iRule against a net resolver forward zone name server that happens to be down can result in the iRule pausing for up to a few minutes.


The connection to the virtual server is paused for a significant amount of time.


Nameserver configures as fwd-zone in net resolver should be down.


Use a pool of dns-servers, and configure the pool to monitor the backend dns servers and load balance to healthy pool members.

Fix Information


Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips