Bug ID 781445: named or dnscached cannot bind to IPv6 address

Last Modified: Oct 06, 2020

Bug Tracker

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

Known Affected Versions:
14.1.0,,,,,, 14.1.2, 15.0.0, 15.0.1,,,,

Fixed In:

Opened: May 10, 2019
Severity: 4-Minor


In some scenarios, the named process cannot bind to IPv6 addresses. This occurs because the dnscached process listens to the wildcard IPv6 address port 53 (i.e., :::53) so it cannot respond to queries sent to IPv6 addresses. Following message is reported in ltm log: err named[16593]: binding TCP socket: address in use.


The named process does not respond to the queries that are sent to IPv6 addresses at port 53.


-- The named and dnscached processes are not running. -- The dnscached process is started first. -- The named process is started later.


1) Stop both named and dnscached process. 2) Edit the startup script for dnscached to start in IPv4-only mode. 2a) On BIG-IP system, open the file /etc/bigstart/startup/dnscached. 2b) Add "-4" to the command line option of dnscached. 3) Restart the processes: bigstart restart named dnscached

Fix Information

The dnscached startup script has been modified to start in IPv4-only mode, so it does not listen on any IPv6 address.

Behavior Change