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

Last Modified: Oct 04, 2024

Affected Product(s):
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, 15.1.4.1, 15.1.5, 15.1.5.1, 15.1.6, 15.1.6.1, 15.1.7, 15.1.8, 15.1.8.1, 15.1.8.2, 15.1.9, 15.1.9.1, 15.1.10, 15.1.10.2, 15.1.10.3, 15.1.10.4, 15.1.10.5, 16.0.0, 16.0.0.1, 16.0.1, 16.0.1.1, 16.0.1.2, 16.1.0, 16.1.1, 16.1.2, 16.1.2.1, 16.1.2.2, 16.1.3, 16.1.3.1, 16.1.3.2, 16.1.3.3, 16.1.3.4, 16.1.3.5, 16.1.4, 16.1.4.1, 16.1.4.2, 16.1.4.3, 16.1.5, 16.1.5.1

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

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips