# Bizarre DNS problem

## Jiokah

Hey,

I'm having a rather odd problem with the DNS on my gentoo box. Among other things, I'm using the box as a router. The problem I'm encountering is that, at seemingly random times, certain domains just don't exist anymore! So for example, somedomain.com does not resolve to anything, when it's IP address works just fine. Right now it's been doing it with google.com, but what's different about this is that accessing google.ca fixes it! I've been getting around this problem by just using the hosts file to bypass connecting with a DNS name, but an IP address instead. This problem only occurs with machines recieving internet through the gentoo box, when accessing these address on the box itself, I find no problem at all.

So, naturally, I'm horribly confused at this point. Any help would be very much appreciated!

Thanks!

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## mlivingstone

 *Jiokah wrote:*   

> Hey,
> 
> I'm having a rather odd problem with the DNS on my gentoo box. Among other things, I'm using the box as a router. The problem I'm encountering is that, at seemingly random times, certain domains just don't exist anymore! So for example, somedomain.com does not resolve to anything, when it's IP address works just fine. Right now it's been doing it with google.com, but what's different about this is that accessing google.ca fixes it! I've been getting around this problem by just using the hosts file to bypass connecting with a DNS name, but an IP address instead. This problem only occurs with machines recieving internet through the gentoo box, when accessing these address on the box itself, I find no problem at all.
> 
> 

 

When google.com disappears, do other *.com addresses go too? When google.com goes, if you do a 

traceroute google.com

nslookup google.com

what does it say?

Are you running your own dns relay or using your ISP's servers? 

Cheers,

MarkL

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## Jiokah

 *mlivingstone wrote:*   

> When google.com disappears, do other *.com addresses go too?

 

Nope, there doesn't seem to be any synchronicity here, random domains go at random times - and come back at random times.

 *mlivingstone wrote:*   

> When google.com goes, if you do a 
> 
> traceroute google.com
> 
> nslookup google.com
> ...

 

The only machine I can use to do this is the gentoo box itself (on which this problem doesn't exist), all other machines are windows. The next time a domain disappears I'll throw in a LiveCD and check it out.

 *mlivingstone wrote:*   

> Are you running your own dns relay or using your ISP's servers?

 

ISP's

Thanks  :Smile: 

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## mlivingstone

Arg, it's too early in the day to figure out multiple level quotes  :Wink: 

you can use 

tracert google.com

nslookup google.com

pathping google.com

in windows.

You can also do

ipconfig/all

to see some settings.

HTH

MarkL

----------

## zeek

Windows remembers DNS failures for 5 mins.  When this happens try flushing the DNS cache with:

```

ipconfig /flushdns

```

----------

## ChipB

Hi,

Once I had bizzare behavior of DNS where /etc/resolv.conf would be overwritten, disabling DNS, every 5 min.

I fixed it by rebooting. This was one of the very few linux problems I fixed via reboot.

More generally,

You might check your /etc/resolv.conf

Personally, I use openDNS

via

nameserver 208.67.222.222

nameserver 208.67.220.220

generally dhcpcd resets it automatically, so to use a static resolv.conf like I need to turn off the resetting.

Good luck,

Chip

----------

## Jiokah

Ok, it happened again just now. Turns out google.com works just fine, but www.google.com doesn't.

nslookup:

```

Name:    google.com

Addresses:  72.14.207.99, 64.233.187.99, 64.233.167.99

Name:    www.google.com (didn't give addresses)

```

tracert:

```

Tracing route to google.com [72.14.207.99]

over a maximum of 30 hops:

  1     1 ms     1 ms    <1 ms  192.168.2.1

  2     1 ms     1 ms     1 ms  192.168.0.1

  3     8 ms     7 ms    12 ms  10.148.32.1

...

Unable to resolve target system name www.google.com.

```

but on the gentoo box itself:

```

 # ping www.google.com

PING www.l.google.com (72.14.205.104) 56(84) bytes of data.

64 bytes from qb-in-f104.google.com (72.14.205.104): icmp_seq=1 ttl=247 time=8.3                                                                              7 ms

64 bytes from qb-in-f104.google.com (72.14.205.104): icmp_seq=2 ttl=247 time=11.                                                                              0 ms

--- www.l.google.com ping statistics ---

2 packets transmitted, 2 received, 0% packet loss, time 999ms

rtt min/avg/max/mdev = 8.376/9.719/11.062/1.343 ms

```

OK, now all I have to do to fix this is type in "http://www.google.ca" in firefox, and now:

```

Pinging www.google.com [72.14.205.147] with 32 bytes of data:

Reply from 72.14.205.147: bytes=32 time=9ms TTL=245

Reply from 72.14.205.147: bytes=32 time=8ms TTL=245

```

I tried "ipconfig /flushdns" but to no avail.

So this time, www.google.com didn't resolve and google.com did. This happens every now and then with my domains too (and my zone files aren't the problem).

Would someone at least be able to explain why accessing google.ca would temporarily fix the problem? It doesn't quite make sense.

Thanks for all the help!!

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## Jiokah

Ok I know this thread is getting old, but just in case any body gets the same problem as I had, I found the solution.

Turns out the DNS from my ISP (Rogers) is just really, REALLY crappy. So I changed my DNS servers from automatic (from DHCP) to Verizon's DNS servers (4.2.2.1 and 4.2.2.2). Not only is DNS working good for me now, it's actually insanely fast too, before I always had to wait a second or two for a host to resolve and now it's instant.

Hope this helps someone

-Matthew

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## mno

If you're a Rogers customer, I'm not sure it's such a good idea to use Verizon's DNS. If that's the case, then I'd suggest you use the OpenDNS alternative, or you can run your own local DNS server...

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## Jiokah

Hey thanks for the suggestion, I've switched to OpenDNS. I just found two IP addressed at the bottom of the site in big orange bold text so I presume those are the addresses to use.

Just curious though, why wouldn't verizon be a good idea?

Thanks  :Smile: 

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## masseya

If Verizon isn't your ISP, they don't have a contractual agreement to allow you to use their DNS servers.  They may or may not care, but they could simply not respond to you and you would have no recourse.

On the other hand, OpenDNS is a great solution.  See this Wired.com article for a couple compelling reasons why.

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