1. watchA
Contents
3台中の1台だけがTCP接続に返答をする。
$ dig +tcp ns1.dreamhost.com @208.97.182.10 ; <<>> DiG 9.12.1 <<>> +tcp ns1.dreamhost.com @208.97.182.10 ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 51250 ;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 ;; WARNING: recursion requested but not available ;; QUESTION SECTION: ;ns1.dreamhost.com. IN A ;; ANSWER SECTION: ns1.dreamhost.com. 300 IN A 64.90.62.230 ;; Query time: 343 msec ;; SERVER: 208.97.182.10#53(208.97.182.10) ;; WHEN: Tue Apr 24 20:35:47 JST 2018 ;; MSG SIZE rcvd: 51 $ dig +tcp ns1.dreamhost.com @64.90.62.230 ;; Connection to 64.90.62.230#53(64.90.62.230) for ns1.dreamhost.com failed: timed out. tmaeno@u16:~$ dig +tcp ns3.dreamhost.com @66.33.205.230 ;; Connection to 66.33.205.230#53(66.33.205.230) for ns3.dreamhost.com failed: timed out.
$ dig +tcp -t ns dreamhost.com @208.97.182.10 ; <<>> DiG 9.12.1 <<>> +tcp -t ns dreamhost.com @208.97.182.10 ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 43454 ;; flags: qr aa rd; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 3 ;; WARNING: recursion requested but not available ;; QUESTION SECTION: ;dreamhost.com. IN NS ;; ANSWER SECTION: dreamhost.com. 14400 IN NS ns1.dreamhost.com. dreamhost.com. 14400 IN NS ns2.dreamhost.com. dreamhost.com. 14400 IN NS ns3.dreamhost.com. ;; ADDITIONAL SECTION: ns1.dreamhost.com. 300 IN A 64.90.62.230 ns2.dreamhost.com. 300 IN A 208.97.182.10 ns3.dreamhost.com. 300 IN A 66.33.205.230 ;; Query time: 336 msec ;; SERVER: 208.97.182.10#53(208.97.182.10) ;; WHEN: Tue Apr 24 20:38:13 JST 2018 ;; MSG SIZE rcvd: 133