I am using my Nokia 5800 XpressMusic for this, which runs Symbian S60 version 5, and it may be slightly different for other phones. Also, I am doing this for just one access point here. You need to change it for every access point seperately.
First, go to the settings. On my S60v5, I went to Connectivity. Here, I tapped Destinations. What you need to do for this step is to get to the list of different access points you use, for example your mobile Internet connection and maybe a Wi-Fi network at your home, school or work.
Here, choose an access point. Edit it. Tap Options and then go to Advanced Settings.
In the Advanced Settings screen, tap twice DNS addresses to change it to User defined. A small box will pop-up. Here, enter two DNS server IP addresses.
Hit OK and close everything. Now again, you might want to change this for all the access points you have. I suggest you use the DNS server that was suggested by namebench in my old post, because it is optimized for your location. It'll work good for you, as you probably use your phone in place you live in (duh!).
Good luck. And do check out my previous posts too, in the archive.
