Dig is a DNS lookup utility provided by ISC. This page is a simple web interface for dig.
$ dig 46.203.127.72 PTR ; <<>> DiG 9.11.3-1ubuntu1.2-Ubuntu <<>> 46.203.127.72 PTR ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 9388 ;; flags: qr rd ra ad; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 4096 ;; QUESTION SECTION: ;46.203.127.72. IN PTR ;; AUTHORITY SECTION: . 50908 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2018101801 1800 900 604800 86400 ;; Query time: 48 msec ;; SERVER: 139.162.69.5#53(139.162.69.5) ;; WHEN: Fri Oct 19 04:34:33 UTC 2018 ;; MSG SIZE rcvd: 117