>;; QUESTION SECTION: >;spamhaus.relays.osirusoft.com. IN A > >;; QUESTION SECTION: >;248.217.80.64.spamhaus.relays.osirusoft.com. IN A > >;; ANSWER SECTION: >248.217.80.64.spamhaus.relays.osirusoft.com. 23931 IN A 127.0.0.6 > > >Inquiring minds want a DNS lesson... Regardless of what Joe Jared does (or >I guess -because- of what he does) with his DNS, how does my caching >nameserver figure the one out but not the other? I'm assuming the first >[non]answer is simply because there is no PTR record. But I thought to >even do the second dig, one has to be able to find the first...
The key is that DNS works a bit differently than might be expected. To look up the A record for 248.217.80.64.spamhaus.relays.osirusoft.com, the DNS resolver goes to the root servers and asks them for the A record for 248.217.80.64.spamhaus.relays.osirusoft.com. They respond that you have to go to one of the the .com root servers; the DNS resolver then asks them for the A record for 248.217.80.64.spamhaus.relays.osirusoft.com. They know the NS records for osirusoft.com (but don't know or care of there is a zone spamhaus.relays.osirusoft.com), and tell the DNS resolver to look there. Normally, at this point, the NS records for osirusoft.com would respond with a referral to the NS records for spamhaus.relays.osirusoft.com, and the DNS resolver would go there. But, the way it is set up here, the osirusoft.com nameservers are authoritative for 248.217.80.64.spamhaus.relays.osirusoft.com and will return the answer for it. So even though the spamhaus.relays.osirusoft.com zone doesn't really exist (there are no DNS entries for it), you can still look up 248.217.80.64.spamhaus.relays.osirusoft.com. ############################################################# This message is sent to you because you are subscribed to the mailing list <[EMAIL PROTECTED]>. To unsubscribe, E-mail to: <[EMAIL PROTECTED]> To switch to the DIGEST mode, E-mail to <[EMAIL PROTECTED]> To switch to the INDEX mode, E-mail to <[EMAIL PROTECTED]> Send administrative queries to <[EMAIL PROTECTED]>
