If you are on Sprint... I'm Pretty sure you are experiencing a placebo effect because they override all dns queries to their dns servers.
Test what dns servers you are actually using with one of these 2 methods:
Open this site: (use Internet Explorer Mobile because Opera uses a proxy)
www.dslreports.com/mspeed > click link "your IP"
Also, you can test this out using FdcSoft TaskManager (I have v3.1)
Go to the IPConfig tab > select IPConfig/All from the dropdown menu
Then scroll to your "PPP adapter Cellular Line"
Good luck.
I tried this on my Mogul when I first got it last year in both EPST and in Settings > Connections and in both cases Sprint had overridden my settings.