; dig +trace +additional bbc.co.uk NS ; bbc.co.uk. NS uk. 172800 IN NS nsa.nic.uk. uk. 172800 IN NS nsb.nic.uk. uk. 172800 IN NS nsc.nic.uk. uk. 172800 IN NS nsd.nic.uk. uk. 172800 IN NS dns1.nic.uk. uk. 172800 IN NS dns2.nic.uk. uk. 172800 IN NS dns3.nic.uk. uk. 172800 IN NS dns4.nic.uk. nsa.nic.uk. 172800 IN A 156.154.100.3 nsb.nic.uk. 172800 IN A 156.154.101.3 nsc.nic.uk. 172800 IN A 156.154.102.3 nsd.nic.uk. 172800 IN A 156.154.103.3 dns1.nic.uk. 172800 IN A 213.248.216.1 dns2.nic.uk. 172800 IN A 103.49.80.1 dns3.nic.uk. 172800 IN A 213.248.220.1 dns4.nic.uk. 172800 IN A 43.230.48.1 nsa.nic.uk. 172800 IN AAAA 2001:502:ad09::3 nsb.nic.uk. 172800 IN AAAA 2001:502:2eda::3 nsc.nic.uk. 172800 IN AAAA 2610:a1:1009::3 nsd.nic.uk. 172800 IN AAAA 2610:a1:1010::3 dns1.nic.uk. 172800 IN AAAA 2a01:618:400::1 dns2.nic.uk. 172800 IN AAAA 2401:fd80:400::1 dns3.nic.uk. 172800 IN AAAA 2a01:618:404::1 dns4.nic.uk. 172800 IN AAAA 2401:fd80:404::1 ;; Received from h.root-servers.net. (198.97.190.53) for . in 7.8ms, NOERROR bbc.co.uk. 172800 IN NS dns1.bbc.co.uk. bbc.co.uk. 172800 IN NS ddns0.bbc.co.uk. bbc.co.uk. 172800 IN NS dns0.bbc.co.uk. bbc.co.uk. 172800 IN NS ddns1.bbc.co.uk. bbc.co.uk. 172800 IN NS dns1.bbc.com. bbc.co.uk. 172800 IN NS ddns0.bbc.com. bbc.co.uk. 172800 IN NS dns0.bbc.com. bbc.co.uk. 172800 IN NS ddns1.bbc.com. dns0.bbc.co.uk. 172800 IN A 198.51.44.9 dns1.bbc.co.uk. 172800 IN A 198.51.45.9 ddns0.bbc.co.uk. 172800 IN A 148.163.199.1 ddns1.bbc.co.uk. 172800 IN A 148.163.199.65 dns0.bbc.co.uk. 172800 IN AAAA 2620:4d:4000:6259:7:9:0:1 dns1.bbc.co.uk. 172800 IN AAAA 2a00:edc0:6259:7:9::2 ddns0.bbc.co.uk. 172800 IN AAAA 2607:f740:e04e::1 ddns1.bbc.co.uk. 172800 IN AAAA 2607:f740:e04e:4::1 ;; Received from nsa.nic.uk. (156.154.100.3) for uk. in 8.7ms, NOERROR bbc.co.uk. 900 IN NS dns0.bbc.co.uk. bbc.co.uk. 900 IN NS dns0.bbc.com. bbc.co.uk. 900 IN NS dns1.bbc.co.uk. bbc.co.uk. 900 IN NS dns1.bbc.com. bbc.co.uk. 900 IN NS ddns0.bbc.co.uk. bbc.co.uk. 900 IN NS ddns0.bbc.com. bbc.co.uk. 900 IN NS ddns1.bbc.co.uk. bbc.co.uk. 900 IN NS ddns1.bbc.com. ;; Received from ddns1.bbc.com. (148.163.199.193) for bbc.co.uk. in 8.5ms, NOERROR aa ;; authoritative servers for bbc.co.uk. ;; MATCH ddns1.bbc.com. 148.163.199.193 NOERROR serial 2026092101 8.3ms ddns0.bbc.co.uk. ddns0.bbc.com. ddns1.bbc.co.uk. ddns1.bbc.com. dns0.bbc.co.uk. dns0.bbc.com. dns1.bbc.co.uk. dns1.bbc.com. ;; MATCH dns0.bbc.co.uk. 198.51.44.9 NOERROR serial 2026092101 8.2ms ddns0.bbc.co.uk. ddns0.bbc.com. ddns1.bbc.co.uk. ddns1.bbc.com. dns0.bbc.co.uk. dns0.bbc.com. dns1.bbc.co.uk. dns1.bbc.com. ;; MATCH dns0.bbc.com. 198.51.44.73 NOERROR serial 2026092101 8.6ms ddns0.bbc.co.uk. ddns0.bbc.com. ddns1.bbc.co.uk. ddns1.bbc.com. dns0.bbc.co.uk. dns0.bbc.com. dns1.bbc.co.uk. dns1.bbc.com. ;; MATCH ddns0.bbc.co.uk. 148.163.199.1 NOERROR serial 2026092101 8.2ms ddns0.bbc.co.uk. ddns0.bbc.com. ddns1.bbc.co.uk. ddns1.bbc.com. dns0.bbc.co.uk. dns0.bbc.com. dns1.bbc.co.uk. dns1.bbc.com. ;; MATCH dns1.bbc.co.uk. 198.51.45.9 NOERROR serial 2026092101 131.5ms ddns0.bbc.co.uk. ddns0.bbc.com. ddns1.bbc.co.uk. ddns1.bbc.com. dns0.bbc.co.uk. dns0.bbc.com. dns1.bbc.co.uk. dns1.bbc.com. ;; MATCH ddns0.bbc.com. 148.163.199.129 NOERROR serial 2026092101 8.6ms ddns0.bbc.co.uk. ddns0.bbc.com. ddns1.bbc.co.uk. ddns1.bbc.com. dns0.bbc.co.uk. dns0.bbc.com. dns1.bbc.co.uk. dns1.bbc.com. ;; MATCH dns1.bbc.com. 198.51.45.73 NOERROR serial 2026092101 131.3ms ddns0.bbc.co.uk. ddns0.bbc.com. ddns1.bbc.co.uk. ddns1.bbc.com. dns0.bbc.co.uk. dns0.bbc.com. dns1.bbc.co.uk. dns1.bbc.com. ;; MATCH ddns1.bbc.co.uk. 148.163.199.65 NOERROR serial 2026092101 8.7ms ddns0.bbc.co.uk. ddns0.bbc.com. ddns1.bbc.co.uk. ddns1.bbc.com. dns0.bbc.co.uk. dns0.bbc.com. dns1.bbc.co.uk. dns1.bbc.com. ;; public resolvers ;; MATCH Cloudflare 1.1.1.1 NOERROR ttl 287 10.4ms ddns0.bbc.co.uk. ddns0.bbc.com. ddns1.bbc.co.uk. ddns1.bbc.com. dns0.bbc.co.uk. dns0.bbc.com. dns1.bbc.co.uk. dns1.bbc.com. ;; MATCH Google 8.8.8.8 NOERROR ttl 211 9ms ddns0.bbc.co.uk. ddns0.bbc.com. ddns1.bbc.co.uk. ddns1.bbc.com. dns0.bbc.co.uk. dns0.bbc.com. dns1.bbc.co.uk. dns1.bbc.com. ;; MATCH Quad9 9.9.9.9 NOERROR ttl 716 7.8ms ddns0.bbc.co.uk. ddns0.bbc.com. ddns1.bbc.co.uk. ddns1.bbc.com. dns0.bbc.co.uk. dns0.bbc.com. dns1.bbc.co.uk. dns1.bbc.com. ;; MATCH OpenDNS 208.67.222.222 NOERROR ttl 900 8.9ms ddns0.bbc.co.uk. ddns0.bbc.com. ddns1.bbc.co.uk. ddns1.bbc.com. dns0.bbc.co.uk. dns0.bbc.com. dns1.bbc.co.uk. dns1.bbc.com. PASS Authoritative answer: ddns0.bbc.co.uk., ddns0.bbc.com., ddns1.bbc.co.uk., ddns1.bbc.com., dns0.bbc.co.uk., dns0.bbc.com., dns1.bbc.co.uk., dns1.bbc.com. From the servers for bbc.co.uk., TTL 15m 0s. This is what every resolver converges on. PASS Delegation: 8 nameservers The parent zone and the zone itself list the same nameservers. PASS Glue: 8 of 8 records match Every address the parent hands out for the nameservers matches what the zone itself publishes. PASS Authoritative servers: 8 of 8 answered Every nameserver in the delegation responded. PASS Zone serial: 2026092101 on every server All nameservers hold the same version of the zone. PASS Public resolvers: 4 of 4 match Cloudflare, Google, Quad9 and OpenDNS all return the authoritative answer. If a user still sees something else, their ISP's resolver or their own machine is caching it. ;; All 4 resolvers agree with the authoritative servers