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

Last Modified: Oct 25, 2021

Bug Tracker

Affected Product:  See more info
BIG-IP TMOS(all modules)

Known Affected Versions:
15.1.0, 15.1.0.1, 15.1.0.2, 15.1.0.3, 15.1.0.4, 15.1.0.5, 15.1.1, 15.1.2, 15.1.2.1, 15.1.3, 15.1.3.1, 15.1.4, 16.0.0, 16.0.0.1, 16.0.1, 16.0.1.1, 16.0.1.2, 16.1.0

Opened: May 22, 2020
Severity: 3-Major

Symptoms

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.

Impact

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

Conditions

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

Workaround

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

None

Behavior Change