Strange (router dependent?) DNS problems

Discussion in 'General Discussion' started by Anonymous, Dec 29, 2005.

  1. Anonymous

    Anonymous Guest


    Recently i'm having real strange problems regarding my network. I've been using a Netgear MR814v2 router for more than one year without having problems. However, during the last few weeks i had serious problem resolving domain names. So i got a new router (because bypassing the router resulted in correct name resolution so i thought the router might be broken) - Linksys WRT54GSv4.

    I'm using dd-wrt v23 and still have a strange network problem. I cant resolve SOME names, regardless what i'm doing. I'll give you an example:

    I can't connect to e.g. when using the default (dhcp derived) settings. whenever i force my desktop pc to use my (means my ISPs) dns server (the same that is used by the router) instead of (the router) it works. "All" other addresses work. And the next day it appears not to be the same address again but rather another - thats WEIRD! And the REALLY strange thing is - SSHing my router i can ping "all" domains EXCEPT - in this case - I get an error "Unknown host" immediately.

    Does anyone have ANY ideas? Its obviously NOT firmware derived. Furthermore, is there any chance to see the duplex settings of the WAN port? maybe that is making some problems?

    thanks in advance
  2. Anonymous

    Anonymous Guest

  3. NateHoy

    NateHoy Network Guru Member

    I've found similar problems with other Linksys routers. The only way I was able to resolve my problems was to put the DNS servers into the router itself, so the router doesn't try to look them up from the ISP. Why this works, I don't know, but if I do that I can use DNS cache on the router just fine.

    I haven't even tried NOT keying the DNS servers into my current router (WRT54G V4, HyperWRT Tofu 10), since I found DNS servers that were faster and more reliable than my ISP's ( - are public DNS servers), so I don't want to take the settings from my ISP anyway.
  4. Anonymous

    Anonymous Guest

    I have entered all of my IPs manually - DHCP is somehow screwed (strange, too :))). nevertheless - i CAN ping the DNS from the router, I CAN ping e.g. from my desktop (behind the router) when manually overwriting the DNS ( -> but i CANNOT ping from the router! although i CAN ping!

    Beside the q for checking the duplex settings - is there any possibility to check the MTU size when set to "auto"?
  5. NateHoy

    NateHoy Network Guru Member

    In HyperWRT, the MTU size is displayed in the GUI when set to Auto. I've never run DD-WRT, so others can help you there, hopefully.

    In the meantime...

    If you can get to a command line, you can always run this:

    nvram show | grep mtu

    Which will show all nvram entries that have the letters "mtu" in them, which should include your various MTU settings.
  6. Anonymous

    Anonymous Guest

    thanks for the hint... nevertheless - i discovered its obviously NOT MTU size that makes these troubles - damn... any suggestions :)?
  7. Anonymous

    Anonymous Guest

    another idea - i might have to set my wan port to 10MBit/full duplex. any suggestions how i could manage that? thanks
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