halting dns server refresh

jon23d · 10-20-2006, 05:26 PM

I noticed the other day that when I surf the web it is taking about a minute and a half for name resolution to take place, totally insane when I'm running 10mbps... So I call my ISP - the first person I talk to tells me that I need to call my computer manufacturer. I tell her that she's nuts and that is what my isp handles.

She escalates the call and I finally get through to somebody who just gives me an alternate ip for the servers. Everything is working beautifully now, except...

Every once in a while my network settings seem to refresh and I lose the changes. Is there a way to stop this from happening?

I'm using a cable modem connected directly to the computer.

fordeck · 10-20-2006, 05:48 PM

You are probably using DHCP through your ISP, which may also send out your DNS servers. So when your DHCP lease is up it renews with the default name servers. Have you noticed if the IP address change back to the originals when your DNS slows down?

jon23d · 10-20-2006, 05:51 PM

Yes, and I would like to stop this from happening. I don't ever get a new ip address, but the dns servers keep reverting.

fordeck · 10-20-2006, 06:02 PM

Have you tried putting the good DNS servers in your /etc/resolv.conf file?

jon23d · 10-20-2006, 06:19 PM

Yes, but they are still overwritten when the refresh goes through.

binary_y2k2 · 10-20-2006, 07:00 PM

try adding this to /etc/dhcp3/dhclient.conf

Code:

interface "eth0" {
  supersede domain-name-servers IP_OF_DNS1,IP_OF_DNS2,IP_OF_DNS3;
}

and have a look at

Code:

man dhclient.conf

for more advanced options.

jon23d · 10-20-2006, 08:36 PM

That did appear to work, but then for whatever reason I couldn't get any name resolution to take place. I'm certain this is the right path though, thank you!

fragos · 10-21-2006, 07:01 PM

Linux comes configured by default to support IPv4 and IPv6 at the same. Its starts by trying IPv6 for DNS access and when that fails it trys IPv4. Basically, no body uses IPv6 on the open Internet and you have to wait for time out on IPv6 before every DNS access. Communication with the site you wanted will occur in IPv4 without all the useless handshaking. Disable IPv6 and your performance will improve. Also DNS response time varies by ISP. Comcast is amongst the fastest and Earthlink has a slow DNS process.