Bug ID 1038921: iRule command RESOLV::lookup fails to connect to the specified target virtual server after the destination of the virtual server is modified.

Last Modified: Nov 25, 2022

Bug Tracker

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

Known Affected Versions:

Fixed In:
17.0.0, 16.1.1, 15.1.4

Opened: Aug 05, 2021
Severity: 3-Major


The RESOLV::lookup iRule command fails to connect to the specified target virtual server for DNS resolving purposes. If a tcpdump is collected at the time of the issue, the BIG-IP system can also be seen trying to reach the target virtual server externally, over the network (for example, by sending out ARP requests for the IP address formerly associated with the virtual server).


DNS resolutions will fail. Extraneous traffic (for destinations formerly internal to the BIG-IP system) is seen on the network.


-- Usage of the RESOLV::lookup iRule command against a virtual server. -- The destination IP address of the target virtual server is changed to a new value. -- The iRule command is called repeatedly (with no pause greater than about 30 seconds).


You can work around this issue by performing either of the following actions: - Restart TMM (this will incur in a brief traffic interruption, and a failover on redundant units). - Ensure the RESOLV::lookup iRule command is not called against the modified virtual server for about a minute.

Fix Information


Behavior Change