Bug ID 2153893: With DNS64 configured, resolution aborts early on the first error response without trying other name servers.

Last Modified: Dec 11, 2025

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

Known Affected Versions:
17.1.2.1, 17.1.2.2, 17.1.3

Opened: Nov 20, 2025

Severity: 3-Major

Symptoms

When multiple name servers for a zone are known, as soon as one name server responds with an error rcode, resolution is aborted and other name server are not tried.

Impact

DNS resolution will intermittently fail. DNS resolution will succeed only if the cache randomly selects a working name server to contact first.

Conditions

-- DNS64 is configured. -- More than one name server is configured for a zone. -- One name server responds with an error rcode.

Workaround

Disable DNS64.

Fix Information

None

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips