Hi everybody, Your input on the initial implementation described below would be most appreciated. I see this as a dns operations issue since it does not describe an on-the wire change, except when we do AXFR perhaps. It is mostly a feature.
However, even features could have interoperability issues, and it would be nice if we were aligned. The last forwared paragraph below says "Please let us know your thoughts based on the semantics outlined above. Would this work for you? Do you miss anything? Is there a need for multiple ALIAS statements for load balancing? Are we needlessly incompatible with existing implementations? Is there standardization work we could align against?" Thanks! Bert ----- Forwarded message from bert hubert <bert.hub...@netherlabs.nl> ----- Date: Sun, 21 Sep 2014 12:54:07 +0200 From: bert hubert <bert.hub...@netherlabs.nl> To: pdns-us...@mailman.powerdns.com Subject: [Pdns-users] Please test: ALIAS/ANAME apex record in PowerDNS Hi everybody, Based on strong user interest, we are fast-tracking the implementation of ALIAS/ANAME records, to solve the 'CNAME at apex' problem. Because of the fast-tracking, we need rapid feedback to see if we got it right (see the end of the mail for details). In short, you can CNAME 'www.yourdomain.com' to a CDN or somewhere else, but you can't CNAME 'yourdomain.com', since that breaks DNS. This blogpost by CloudFlare expands on the problem: https://support.cloudflare.com/hc/en-us/articles/200169056-CNAME-Flattening-RFC-compliant-support-for-CNAME-at-the-root Today, we implemented ALIAS support as an experimental PowerDNS feature, which allows the following: $ORIGIN example.com. @ IN SOA ns1 ahu 2014091619 7200 3600 1209600 3600 @ IN NS ns1 @ IN NS ns2 www IN CNAME xs.powerdns.com. ns1 IN A 1.2.3.4 ns2 IN A 4.3.2.1 @ IN ALIAS www.powerdns.com. @ IN MX 25 outpost.ds9a.nl. elsewhere IN CNAME @ The branch can be found on https://github.com/PowerDNS/pdns/tree/alias and we should have packages soon. The current semantics for the ALIAS pseudo-record are that they only match if no real record did. So in the case above, an MX query for example.com would return "25 outpost.ds9a.nl". But a query for AAAA would return the IPv6 address obtained by following the www.powerdns.com CNAME chain to xs.powerdns.com. This also works for all other record types, btw. Our implementation uses a defined resolver to look up the actually requested record, and adds the data found to the packet built so far. This means that querying 'elsewhere.example.com' will include a CNAME to example.com, which in turn will lead to processing of the ALIAS record. Finally, for TTL, we currently use what the resolver gave us. But perhaps we could use the TTL of the ALIAS record instead, or as a maximum? Or minimum? Please let us know your thoughts based on the semantics outlined above. Would this work for you? Do you miss anything? Is there a need for multiple ALIAS statements for load balancing? Are we needlessly incompatible with existing implementations? Is there standardization work we could align against? Your input is highly welcome! Bert PS: the above is currently not yet supported for DNSSEC domains! -- PowerDNS Website: http://www.powerdns.com/ Contact us by phone on +31-15-7850372 _______________________________________________ Pdns-users mailing list pdns-us...@mailman.powerdns.com http://mailman.powerdns.com/mailman/listinfo/pdns-users ----- End forwarded message ----- _______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www.ietf.org/mailman/listinfo/dnsop