Chris Wedgwood
On Sun, Apr 30, 2000 at 06:10:12PM +1200, Don Stokes wrote:
More to the point, most resolvers process CNAMEs transparently
gethostbyname does (sort of) -- but the resolver code in most MTAs I know of (postfix, sendmail and qmail) has explicit code to deal with CNAME bogosity.
Hmmm. CNAMES are usually returned in the answer section of a reply along with the actual data, so if you have foo IN CNAME bar bar IN A 1.2.3.4 you get both records. So a CNAME as the target of an MX will still work if the name resolution stuff in the client is coded to ignore the CNAME and just process the data parts of the answers section. The alternative is that it can be defensive and actually check that the key of each returned RR matches the key queried for, in which case on stumbling over a CNAME in the answers it needs to change the key it's looking for to the CNAME target. BIND it seems (at least if forwarding is enabled) actually retrieves the targets of CNAMEs, so if you ask for A records, you get any reachable A records, even if the name server being queried only has the CNAME in its local database. -- don --------- To unsubscribe from nznog, send email to majordomo(a)list.waikato.ac.nz where the body of your message reads: unsubscribe nznog