the issue was originally raised on 6bone@isi.edu. there are name server implementations (probably load balancing product) that responds with NXDOMAIN, when it should respond with NOERROR with empty reply. one example is news.bbc.co.uk. this symptom not only confuse IPv6-ready client resolvers, but also has bad effect against negative caching and email delivery (if MX is responded with NODOMAIN). do you know: - name of particular implementation which have/had this bug? - other examples of nameservers that behave like this? (windowsupdate.microsoft.com behaved like this in Feb 2002, but they are already fixed) - how can we get people to fix it? (client side workaround should not be populated, just to be sure) itojun % dig news.bbc.co.uk. aaaa ; <<>> DiG 9.1.2 <<>> news.bbc.co.uk. aaaa ;; global options: printcmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 60945 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;news.bbc.co.uk. IN AAAA ;; ANSWER SECTION: news.bbc.co.uk. 1770 IN CNAME newswww.bbc.net.uk. ;; Query time: 2362 msec ;; SERVER: 127.0.0.1#53(0.0.0.0) ;; WHEN: Thu Apr 25 11:25:45 2002 ;; MSG SIZE rcvd: 62 % dig news.bbc.co.uk. a ; <<>> DiG 9.1.2 <<>> news.bbc.co.uk. a ;; global options: printcmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 11225 ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 2, ADDITIONAL: 2 ;; QUESTION SECTION: ;news.bbc.co.uk. IN A ;; ANSWER SECTION: news.bbc.co.uk. 1761 IN CNAME newswww.bbc.net.uk. newswww.bbc.net.uk. 300 IN A 212.58.240.33 ;; AUTHORITY SECTION: bbc.net.uk. 14360 IN NS ns0.thny.bbc.co.uk. bbc.net.uk. 14360 IN NS ns0.thdo.bbc.co.uk. ;; ADDITIONAL SECTION: ns0.thdo.bbc.co.uk. 6362 IN A 212.58.224.20 ns0.thny.bbc.co.uk. 6362 IN A 38.160.150.20 ;; Query time: 2341 msec ;; SERVER: 127.0.0.1#53(0.0.0.0) ;; WHEN: Thu Apr 25 11:25:53 2002 ;; MSG SIZE rcvd: 156