dns lookups in an iapp template

Yeah - exec is a TCL builtin. For iRules stuff like that isn't available, but in iApps we don't have those sorts of restrictions, so scripts have more of the capabilities of TCL available to them. I think as an admin user you can use any commands other than "interp", though as non-admins the available commands are restricted somewhat.

The web of course is a great place to find documentation about TCL and its builtin functions. In case you're running Debian in your dev environment, the "tcl-doc" package installs manpages for the built-in commands which can be really handy. For example, to see the doc for exec, at a shell I type:

man 3tcl exec

and this gives me everything I need to use that command.

Cheers,

-Brent