Here's a link to the zone on Wowhead: Isle of Quel'Danas - Zone - World of Warcraft
If you look at the url it says zone=4080 - that means the zoneID is 4080.
You could also get HBconsole and write this in the C# console:
Code:
Log("" + Me.ZoneId);
and it'll write the zoneID in the output log below. You can also use this method for other info like Me.MapId for example.