I did a bit of research into OpenDNS a while ago, the link is
here
I've been a little intrigued by what sort of real benefit the likes of OpenDNS might actually have on, so I thought I'd do a bit of a test of, and see what it does.
SO I thought I'd start with the worlds most popular websites, according to http://www.alexa.com/ I got a list of the top 100 global websites.
the basic results turned out to be...
1. OpenDNS server at 208.67.222.222
average = 108.8787879
min = 15
max = 1273
2. my ISP's DNS server at ns0.zen.co.uk
average = 16.9798
min = 13
max = 24
3. a local server running bind 9.2.4 server, having done a rndc flush (this will force a full DNS tree root name resolution - hence the very large times)
average = 828.4747475
min = 43
max = 4983
4. the same server as 3, run without flushing the cache
average = 1.424242424
min = 0
max = 93
which I think is pretty much what I expected! a local ISP's DNS servers will generally be faster than anything elsewhere because they take advantage of being well used and hence having full cache, and being local so traffic doesn't have to go very far.
a local server doing full root DNS resolutions will take the longest to resolve simply because there is a DNS tree that it needs to propagate through.
I've just had a read around the opendns site, and it seems like a marketing thing more than a good technical idea.
they appear to make their money by sending you to an advertising site whenever a name doesn't resolve. to me, this seems a bad idea imagine the scenario - 'hey bob, the kitties getting a bit empty you know' - 'not a prob boss, just let me tweak some dns resolver timings'
also, their idea that they are 'quicker' because they use a 'large' cache is also bobbins. a dns time to live (ttl) is set by the domain owner, and with very good reason. if you host a website that you're about to change the ip address on, the best way to do it, is to set the ttl to zero, so every machine needs a fresh lookup, then as soon as the move is made, every box on the internet automatically finds it. after that you stretch the ttl back to normal again.
if you artificially change the cache time, you'll get a lot more failed lookups (woohoo! more revenue for opendns!!)
my advice, keep with the dns server your isp is giving, it is (usually) at the end of the wire you're connecting over, and unlikely to be thrashed at all, you need a LOT of dns queries to swamp even a mediocre dns server.
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I did a bit of research into OpenDNS a while ago, the link is here
I've been a little intrigued by what sort of real benefit the likes of OpenDNS might actually have on, so I thought I'd do a bit of a test of, and see what it does.
SO I thought I'd start with the worlds most popular websites, according to http://www.alexa.com/ I got a list of the top 100 global websites.
the basic results turned out to be...
1. OpenDNS server at 208.67.222.222 average = 108.8787879 min = 15 max = 1273
2. my ISP's DNS server at ns0.zen.co.uk average = 16.9798 min = 13 max = 24
3. a local server running bind 9.2.4 server, having done a rndc flush (this will force a full DNS tree root name resolution - hence the very large times) average = 828.4747475 min = 43 max = 4983
4. the same server as 3, run without flushing the cache average = 1.424242424 min = 0 max = 93
which I think is pretty much what I expected! a local ISP's DNS servers will generally be faster than anything elsewhere because they take advantage of being well used and hence having full cache, and being local so traffic doesn't have to go very far.
a local server doing full root DNS resolutions will take the longest to resolve simply because there is a DNS tree that it needs to propagate through.
I've just had a read around the opendns site, and it seems like a marketing thing more than a good technical idea.
they appear to make their money by sending you to an advertising site whenever a name doesn't resolve. to me, this seems a bad idea imagine the scenario - 'hey bob, the kitties getting a bit empty you know' - 'not a prob boss, just let me tweak some dns resolver timings'
also, their idea that they are 'quicker' because they use a 'large' cache is also bobbins. a dns time to live (ttl) is set by the domain owner, and with very good reason. if you host a website that you're about to change the ip address on, the best way to do it, is to set the ttl to zero, so every machine needs a fresh lookup, then as soon as the move is made, every box on the internet automatically finds it. after that you stretch the ttl back to normal again.
if you artificially change the cache time, you'll get a lot more failed lookups (woohoo! more revenue for opendns!!)
my advice, keep with the dns server your isp is giving, it is (usually) at the end of the wire you're connecting over, and unlikely to be thrashed at all, you need a LOT of dns queries to swamp even a mediocre dns server.