Am 16.04.2011 23:54, schrieb mouss: >> in fact you should not do this because it needs two dns-queries for >> the sending server everytime and you set the MX only once >> > > I see no difference: > > - with no MX: > 1- lookup MX: none > 2- lookup A for domain > > - with MX: > 1- lookup MX: returns say host.example.com > 2- lookup A for host.example.com
on the first look but in reality one mailserver is hosting many domains if any nameserver has our "barracuda.theounge.net" in his cache he can answer the MX for 200 other domains from his cache would the 200 domains have no MX record the first query would have no result and then the nameserver needs a second one for the a-record which has to be cached for each domain even if it would be the same ip-address additionally: negative dns-hits have a small TTL positive hits usually have a ttl from 1 hour to two days so there is a hughe difference in the background
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