If we are going there, I would want to know how common the configurations are.
There is zero additional overhead for www.example.com Outside this list how common are hierarchies more than 4 levels deep in practice? This isn't a functionality issue, it's purely performance. So I suggest a 5% minimum occurrence threshold for considering any corner cases. And made up examples don't count Sent from my difference engine > On Oct 20, 2014, at 5:06 PM, Tim Wicinski <[email protected]> wrote: > > > > I think part of the work on qname-minimization will spend some time studying > performance, as well as operational issues as Peter brought up. > > It could very well be that what Peter pointed out will be true and there are > operational issues that could cause acceptance. But part of this work will > be to understand and document these effects, correct? > > tim > (finally back home and catching up) > > >> On 10/20/14 5:03 PM, Bob Harold wrote: >> I support the idea of qname minimization, but I think there is a common >> case where it will cause additional DNS round trips, slowing the >> response and increasing the number of packets and queries the servers >> must handle. >> >> Consider “www.host.group.department.example.com >> <http://www.host.group.department.example.com>” where the company’s >> servers are authoritative for the zones: >> >> example.com <http://example.com> >> department.example.com <http://department.example.com> >> group.department.example.com <http://group.department.example.com> >> >> Without minimization (typical today): >> >> 1. Query root for “www.host.group.department.example.com >> <http://www.host.group.department.example.com>”, get list of “com” servers. >> 2. Query a com server for “www.host.group.department.example.com >> <http://www.host.group.department.example.com>”, get list of >> “example.com <http://example.com>” servers. >> 3. Query an example.com <http://example.com> server for >> “www.host.group.department.example.com >> <http://www.host.group.department.example.com>”, get answer. >> >> With minimization: >> >> 1. Query root for “com”, get list of “com” servers. >> 2. Query a com server for “example.com <http://example.com>”, get list >> of “example.com <http://example.com>” servers. >> 3. Query an example.com <http://example.com> server for >> “department.example.com <http://department.example.com>”, get list of >> “department.example.com <http://department.example.com>” servers (which >> happens to be the same as the list of “example.com <http://example.com>” >> servers). >> 4. Query a “department.example.com <http://department.example.com>” >> server (likely the same server as step 3) for >> “group.department.example.com <http://group.department.example.com>”, >> get list of “group.department.example.com >> <http://group.department.example.com>” servers. >> 5. Query a “group.department.example.com >> <http://group.department.example.com>” server for >> “host.group.example.com <http://host.group.example.com>”, get probably >> just an A and/or AAAA record, indicating there is no zone cut at that level. >> 6. Query a “group.department.example.com >> <http://group.department.example.com>” server for >> “www.host.group.department.example.com >> <http://www.host.group.department.example.com>”, get answer. >> >> Note that it takes twice as many queries, and each depends on the >> previous, so it is twice as many round trips. >> >> I realize that caching will reduce the extra queries in many cases, but >> can we estimate the impact of this somehow, to determine if it is >> significant? >> >> -- >> >> Bob Harold >> >> DNS hostmaster, University of Michigan >> >> >> >> _______________________________________________ >> DNSOP mailing list >> [email protected] >> https://www.ietf.org/mailman/listinfo/dnsop > > _______________________________________________ > DNSOP mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/dnsop _______________________________________________ DNSOP mailing list [email protected] https://www.ietf.org/mailman/listinfo/dnsop
