Oct 31, 2008

Speed up your Internet access

From time to time my Internet provider has problems with the network. For this case I have a backup: a Vodafone modem. This modem gives me theoretical 256Kbps speed in my area (again: it is theoretical speed, actual is near 130Kbps). This is quite fast for emergency situations. The only bothering things is that every DNS lookup takes 3-10 seconds, which is obviously unacceptable.

When I got tired of these delays, I thought: "What can I do?" Firsts, I thought that I should probably have a local caching DNS server. I made a quick check and found that it is not necessary with Mac OS X because it already includes a lightweight caching daemon for DNS and many other queries. And it could not help me for new DNS queries anyway.

Next I remembered that I had similar problems with my main Internet provider. I solved those by using alternative DNS servers on my AirPort router. It worked well.So I went to my Vodafone Mobile Connect application and added two new DNS servers provided by OpenDNS.org to my mobile connection. These servers are free, fast and reliable. I know some people are paranoid enough not to use anything that seems to have no obvious catch. But my computer sends DNS queries to my providers, so why would I mind sending them to OpenDNS? I do not mind. So I did it.

The only thing that bothered me now is that OS X configuration showed grayed out DNS servers of my provider before OpenDNS servers. Normally it means it means that servers of my provider will take precedence. Obviously I did not want that. But I could delete them (grayed out!). I went to the Internet and almost immediately found a discussion on the Apple web site that clarified the matter. According to the article manually entered DNS servers take precedence. Should I check that? Yes, I should!

Applico:~ dima$ nslookup
> angel.accio.lv
Server: 208.67.222.222
Address: 208.67.222.222#53

Non-authoritative answer:
Name: angel.accio.lv
Address: 213.21.217.206
> exit


Indeed manually entered servers take precedence. 208.67.222.222 is OpenDNS server (I could also see a secondary server: 208.67.220.220). And I see the considerable speed improvement. DNS lookups takes less than a second now. This is at least 6 times faster than before.

And to be complete, I must tell you that there is a catch in using OpenDNS servers. The catch is simple: if OpenDNS cannot resolve an address, it will give you an address of its own server, where it will clearly tell you that address cannot be resolved. It will also attempt to guess what you meant and propose alternatives (like other domain names). I found these proposals to be good. So even if there is a catch, the catch is good for you and me.

Do you want to try OpenDNS now?

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