[Sysadmins] Eircom DNS

Nick Hilliard nick at netability.ie
Wed Jul 8 09:56:55 IST 2009


On 08/07/2009 08:42, Conall O'Brien wrote:
> I saw one article recommending OpenDNS as a fix, which made me sad.

OpenDNS do a lot of bad things, including wildcard A records, which are 
a particularly nasty trick.

Also, if you use openDNS or other resolvers which aren't hosted on your 
ISPs address space, your general internet connectivity quality may drop 
dramatically, as CDNs (content distribution networks) like Akamai, 
Limelight and so forth, use the address on your DNS resolver to 
determine which local cache to use.  If you use your ISP's resolver, 
you'll be directed to the cache which is topologically closest to you 
(in the case of Akamai, this will be very close indeed).  If you use 
OpenDNS, you'll probably be redirected to some cache service in mainland 
USA or at best somewhere in europe, and both your WWW latency and 
throughput to these CDN serviced sites will drop dramatically.

Nick



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