DNS servers cached and won't go away

I'm having an odd problem that probably has a simple solution that I'm missing. I switched our wireless router to different DNS servers (google's public DNS in lieu of our ISPs). In the router settings, this involved unchecking the "automatic from ISP" checkbox. I've verified that those changes persisted correctly on the router config screen.

However, on both the laptop (win7 ultimate, x64) and my desktop (vista ultimate, x64), if I do an ipconfig/all, all 4 servers are listed: my ISPs DNS servers and google's public DNS servers (in that order). I.e., the output (just the DNS info) is pasted below (note the 8.8.8.x is google's public DNS IPs). I've tried doing an ipconfig/flushdns and some other steps, as well as rebooting.

The problem remains: I can't seem to get rid of the extranous 209.18.47.x DNS IPs.

Ideas, anyone?

DNS Servers . . . . . . . . . . . : 209.18.47.61
                                    209.18.47.62
                                    8.8.8.8
                                    8.8.4.4

Garrett

Posted 2010-01-20T01:53:37.090

Reputation: 196

Answers

ipconfig /flushdns does not do what you think it does. If your computer is not retrieving these values from DHCP:

Start -> Run -> ncpa.cpl
Find your adapter, right click and do "Properties"
Find TCP/IP and do "Properties"
Click "Advanced" and then "DNS"
Remove the DNS entries there

If your computer is retrieving your DNS servers from DHCP you have configured the router incorrectly. You may want to switch to static DNS servers (repeat step 1 to 3 and put the DNS servers into the corresponding window).

ta.speot.is

Posted 2010-01-20T01:53:37.090

Reputation: 13 727

1You keep using that command. I do not think it means what you think it means. – Stephen Jennings – 2010-01-20T02:12:09.623

@Stephen Jennings: classic... ;) – mpeterson – 2010-01-20T02:28:22.080

Good sugs. Seems to be a Windows characteristic (not necessarily a "bug" per se). For now, I went ahead & hard-coded the DNS IPs & that works fine. – Garrett – 2010-01-21T02:47:12.807

I have tried a few things and am unable to replicate this behaviour.

First thing is just to make sure they are not hard coded in your network card, however, I tried manually editing mine and it simply overwrites DHCP entries, not add them in addition to.

My guess this is down to a bug/problem in your router.

If you have the option, try to change from DHCP to hard coded entries for your ISP's ip settings. This will work as long as you are on 24/7 and generally maintain the same ip. If your ip changes regularly, this may not work.

Lastly, if you are getting no where, you may want to just go into network settings for the card and simply put 8.8.8.8 and 8.8.4.4 as your adapters only dns settings.

William Hilsum

Posted 2010-01-20T01:53:37.090

Reputation: 111 572