+1 We once proposed exactly the same mechanism. It wasn't popular.
There's no reason why the parent domain has any particular ability to provide the information you are looking for. Add to that the cases John pointed to where it's going to do harm, and you end up in trouble. There's a tendency to think of the DNS hierarchy as mapping to other hierarchical systems, such as the networks linking a host to the Internet. This is demonstrably not the case. There's an (IAB?) RFC that covers the topic, but I can't remember its number nor find it; I'll leave that to the experts. --Martin > -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf Of > John Leslie > Sent: Monday, 13 July 2009 10:29 PM > To: Song Haibin > Cc: [email protected]; 'TOMSU, Marco'; [email protected] > Subject: Re: [alto] [Alto-disc] [Fwd: New Version Notificationfordraft- > song-alto-server-discovery-01] > > Song Haibin <[email protected]> wrote: > > > > Here is the link for the merged document. More comments are > appreciated! > > > > http://tools.ietf.org/id/draft-song-alto-server-discovery-01.txt > > One quick comment: > ] > ] 5.1.2.1. Using DHCP option for access domain name > ] > ] There are DHCP options (OPTION_V4_ACCESS_DOMAIN and > ] OPTION_V6_ACCESS_DOMAIN) proposed in [I-D.ietf-geopriv-lis- > discovery] > ] to discover the local access domain names. The retrieved access > ] domain name can be used to form a SRV name by prefixing the ALTO > ] service label to the access domain name. If it failed with the SRV > ] lookup with this service name, then it will remove one tag from the > ] left hand of the access domain name and prefix the ALTO service > label > ] to form a new SRV name. It will iterate the process until it > ] succeeds in getting an ATLO server information or failed. > > This iterative process can lead to problems, both in that it will > search towards Top-Level-Domains that have no relation to the network > to which the host is actually attached, and in that (if ALTO usage > grows) > it could generate excessive (and pointless) DNS queries at or near the > Top-Level-Domain servers. > > In particular, note that many of the .us locality servers have > limited bandwidth; and I'm sure there are other Country-Code servers > whose bandwidth is even more limited. > > I recommend caution in applying this strip-the-leftmost tactic even > once, and strongly recommend against applying it iteratively without > limit. > > If used at all, there is a need for a standardized signal to say > "Search no further". > > -- > John Leslie <[email protected]> > _______________________________________________ > alto mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/alto ------------------------------------------------------------------------------------------------ This message is for the designated recipient only and may contain privileged, proprietary, or otherwise private information. If you have received it in error, please notify the sender immediately and delete the original. Any unauthorized use of this email is prohibited. ------------------------------------------------------------------------------------------------ [mf2] _______________________________________________ alto mailing list [email protected] https://www.ietf.org/mailman/listinfo/alto
