For anyone who is experiencing slow DNS lookups...

Thanks!:-)

How would one measure this DNS lookup performance?

BTW, I use openDNS.com's...
208.67.222.222
208.67.220.220

For lookup.

I've had this problem on a G4 PowerMac running Panther, and it still had it after a Tiger upgrade. I just replaced it with a Core Duo MacMini, 10.4.7, same problem of slow DNS lookups (i.e., slow initial start to loading a web page, then it goes quickly). Windows machines on the same subnet have no such problem. I've tried the various suggestions on various forums, none of which worked. I tried:

- turn off IPv6 (no help)
- directly enter my ISPs DNS servers (no help)
- manually configure both IP and DNS (no help, went back to DHCP)
- swear at the computer (a little help, mentally)

After some more reading, I tried resolving some addresses using the host command from the Terminal:

host -v www.apple.com 24.34.240.9

where the IP address is one of the DNS servers for my ISP (Comcast). I got a no server found message! I then tried the second DNS server in the Comcast list (found from my router), also no server found. Tried the third one in Comcast's list of DNS servers, and it worked. Entered it in System Preferences -> Network as a DNS server, and now web browsing is zippy! I verified that the two DNS servers that MacOS couldn't see are also down as far as Windows was concerned (using the nslookup command in windows).

What this tells me is that the OS X algorithm for handling unreachable or slow DNS servers is different from that in Windows. Maybe Windows remembers a bad experience with a DNS server and uses ones that it has success with, while OS X just keeps trying them in order, slowing timing them out until it finds one that works?

This could also explain many of the puzzling symptoms people have been seeing (things work some times, other times not; some people have luck specifying the DNS server manually, others don't). It all depends on what DNS servers got distributed to the Mac via DHCP, and how far down the list you have to go to find one that is responsive.

Anyone reading this forum with technical knowledge of both UNIX and Windows DNS lookup implementations? Is there some way to tweak in MacOS to make it perform more like Windows in this situation (like, maybe shortening the DNS server failure timeout)?

Sounds reasonable tsd11 ! 🙂

Just recently I started having problems with Firefox on my iMac. It's either because of a Mac OX or Firefox upgrade.. not sure. All the other computers on my home network work fine.

I disabled IP6 and added my router to the DNS list and now everything is working great again. Thanks for the suggestion.

How does one determine the router's IP address?

I was having terrible lookup problems (stalling on almost every web access attempt) and someone in this group suggested using the following open IP addresses in the DNS Servers spot:
208.67.222.222
208.67.220.220

IMMEDIATELY I was able to begin accessing web sites. Any thoughts on why this worked?

The other, or neither/none, if that's the case, DNS settings were bad/unconnectable, or it just needed some at all.

Some Routers, Modems, or ISP supply DNS settings, others don't.:-)

After upgrading to OS 10.4.8, my internet connection slowed to a stand still. Before the upgrade everything worked fine, your trick of using the routers IP address in the DNS solved everything.

The internet is running at full speed again.

Thank you so much for posting this!

I also tried the OpenDNS trick above and it worked as well.

Thanks to both of you for posting!