DNS 'leak' until I test for it on Linux

[9Lt4bwuxNkXP 0]

Here's a strange problem. I use openvpn to connect to AirVPN, with the update-resolv-conf script to prevent DNS 'leaks' (I know they "don't happen on Linux", but that's what I'm calling it). After starting the VPN, going to dnsleaktest.com, and hitting the extended test, the first query comes back as 2 and shows both my ISP and Air, and all of the rest come back as 1 showing only Air. If I retest or go to another DNS leak checking site (like ipleak.net) after doing this, only Air is shown. If I go to a different site and check *before* using dnsleaktest.com, it will detect my ISP. If I retest, it still shows my ISP along with Air.

 

In short, I am getting DNS 'leaks' until I test for them using dnsleaktest.com.

 

What could be causing this, and how can I fix it?

 

Edit: It seems that testing with dnsleak.com also 'fixes' it.