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Matthew Attoe · Jan 30, 2010, 07:33 AM

Hi,

I am having some weird issues which I feel may be DNS-related.

When I went to bed last night, as far as I was aware, everything was working fine. I could go to whatever webpage I wanted, nice and quick. I was using OpenDNS 208.67.222.22 208.67.220.220.

When I got up this morning I couldn't get to any webpages, but I didn't get a "you are not connected to the internet message".

After speaking to my ISP, and directly hooking my cable modem to my Mac Pro (ethernet port 1) I was able to get connected to the internet, so I knew my connection was fine. This made me think my router was the culprit.

After some head scratching, I decided as a last-ditch effort, to try my ISPs DNS 194.168.4.100, 194.168.8.100 as I thought perhaps the opendns servers had gone down. This allowed my to connect to the net through my router, from my Mac Pro (10.6.2), MacBook Pro (10.6.2) and iPhone - BUT it is very slow and it doesn't seem to allow me to visit all my favourite websites, some of which I visit several times a day. I thought maybe, by sheer coincidence, all of these websites had gone down all at once. But I can connect to them via 3G on my iPhone, so it is not that. I also cannot access OpenDNS | Internet Navigation And Security using my ISP DNS servers, but I can via 3G on my iPhone as well.

Does anyone have any ideas at all. Or maybe some other DNS servers I can try?

Any help would be really appreciated.

Many thanks in advance,

Matthew

Simon · Jan 30, 2010, 07:38 AM

Google Public DNS
8.8.8.8
8.8.4.4

Matthew Attoe · 08:30 AM

Thanks, Simon.

I've tried the ones you listed and I still can't access toucharcade.com or opendns.com.

I wonder if there is something wrong with my router (D-Link DI-634M)? Is there something in there that I would need/could try to reconfigure?

EDIT: I've just tried using XP through BootCamp and I am having the same issues, which I guess rules out the OS at least

EDIT 2: OK, tried taking the router out of the equation and went back to hooking up the Mac directly to the cable modem. Used DHCP, with the Google DNS numbers and everything is working. So it must be the router, right - but why can I access some pages and not others (it's not like they're pages that I shouldn't be looking at, either

)?

Thanks again,

Matthew

Simon · Jan 30, 2010, 08:59 AM

Yep, seems to be the router.

How about you reset the router to factory settings and try setting it up from scratch.

Matthew Attoe · 09:22 AM

Hi,

I've just tried that in the last 30mins or so, and that doesn't seem to be having any effect - still the same issue

I have noticed something else weird though, that may be related.

Both my Mac Pro (192.168.0.101) and MacBook Pro (192.168.0.103) are connected to the router. I can connect from the MP to the MBP and vice-versa using the Shared section of the Sidebar. However, if I try to ping one from the other, I get a

Request timeout for icmp_seq 0
Request timeout for icmp_seq 1
Request timeout for icmp_seq 2
Request timeout for icmp_seq 3
ping: sendto: No route to host
Request timeout for icmp_seq 4
ping: sendto: Host is down
Request timeout for icmp_seq 5
ping: sendto: Host is down
Request timeout for icmp_seq 6

and so on.

Could that have something to do with it?

EDIT: If I ping the MBP (192.168.0.103) from itself, I get all the replies I could ever want. BUT, if I ping the MP from itself (192.168.0.101 and/or 192.168.0.102 - due to the 2 ethernet ports) I get the time-out errors displayed above?

Frustrated from Norwich

Matthew Attoe · Jan 30, 2010, 11:19 AM

Just came back to see if I had any replies.

Gave it another attempt and now things seem to be a bit better - a couple of the non-working sites are now working correctly. Still no luck with the opendns.com though.

Thanks again, Simon, for your help.

Matthew

Simon · Jan 30, 2010, 11:56 AM

Before you ping make sure you haven't enabled stealth mode in the firewall preferences. With stealth mode enabled a ping will always fail (by design).

Security > Firewall > Advanced

No need to say thanks BTW. After all we haven't solved your issues yet.

Matthew Attoe · Jan 30, 2010, 01:09 PM

Hi again Simon,

OK, it was the stealth mode that was stopping me from pinging myself on the MP - So thanks very much for that. At least I know that doesn't have anything to do with it

But I have know noticed that i cannot purchase/download from the App Store either

I wonder if just buying a new router would sort the issues. I've even triple-checked again this afternoon by plugging the modem straight in to the MP and it works fine (even the App Store).

Cheers,

Matthew

Matthew Attoe · Jan 31, 2010, 05:30 AM

Wow!

After leaving everything turned off last night, it al now seems to be working (turned it back on obviously

)

I wonder just what the hell was going on though.

Thanks again,

Matthew

seanc · Jan 31, 2010, 09:19 AM

I had an issue last week with a customer using Virgin Media's DNS servers. I visited bbc.co.uk/iplayer and started a tv program, it played the BBC trailer, went to load the main program and stopped. From then on I could not access the BBC.co.uk website at all.

The customers PC was using the router as the DNS server. I accessed the routers admin page and changed the DNS servers it was using to OpenDNS and everything started working fine.

Have you specified the DNS servers on your router, or just your Mac?

besson3c · Jan 31, 2010, 01:19 PM

If your DNS servers are resolving the correct IP for the domain, they are not responsible for any failed connectivity to these sites. All the DNS servers do is map domains -> IPs.

Have you tried traceroutes? Traceroutes are not definitive tests since many domains block ICMP (ping) packets that traceroutes use, but this might give you an idea *where* this bottleneck is. If it is outside of your local area network, this connectivity problem is completely out of your hands (i.e. not your router's fault).