It's a stupid question, but... Are you even in control of the settings of your reverse DNS? You can only set the reverse DNS at your ISP/Webhost. So, if you rent the IP 46.101.84.103, it is the DNS server at Digital Ocean Inc, that will reply to these reverse queries. Your DNS, that resolves whatever.example.com to 46.101.84.103 cannot do the reverse DNS.
You might have configured a DNS that does this (evidently that's possible and that might be your localhost), but the Internet will never ask this server, because that IP range belongs to your ISP/webhost.
That's because some DNS servers are "authorative" for certain resources. If you own a domain name, you can set the "authoritative" DNS servers for that doman at your registrar (or use the registrars DNS). For example, if I do:
$ dig tude.lu
; <<>> DiG 9.10.3-P4-Ubuntu <<>> tude.lu
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 53410
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 3
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;tude.lu. IN A
;; ANSWER SECTION:
tude.lu. 300 IN A 85.93.203.237
;; AUTHORITY SECTION:
tude.lu. 43200 IN NS dns2.jawtheshark.net.
tude.lu. 43200 IN NS dns1.jawtheshark.net.
;; ADDITIONAL SECTION:
dns1.jawtheshark.net. 411 IN A 149.154.152.102
dns2.jawtheshark.net. 579 IN A 162.252.172.158
;; Query time: 133 msec
;; SERVER: 127.0.1.1#53(127.0.1.1)
;; WHEN: Mon Aug 08 20:54:46 CEST 2016
;; MSG SIZE rcvd: 137
You notice the "authority section"? Well, in a DNS query, that means that anything regarding tude.lu, must be asked from one of those two servers (dns1.jawtheshark.net and dns2.jawtheshark.net). Your local DNS may cache the results, but ultimately, only those two servers can be trusted to give correct results. They are "authoritative".
That's for domain names (basically, "normal" DNS queries). For IP ranges, the same exists. The thing is: an IP range is not linked to a domain at all. The IP range is another resource all together. So, let's take the IP you gave. Who is authoritative?
$ dig -x 46.101.84.103
; <<>> DiG 9.10.3-P4-Ubuntu <<>> -x 46.101.84.103
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 65419
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;103.84.101.46.in-addr.arpa. IN PTR
;; AUTHORITY SECTION:
84.101.46.in-addr.arpa. 1466 IN SOA ns1.digitalocean.com. hostmaster.84.101.46.in-addr.arpa. 1470460984 10800 3600 604800 1800
;; Query time: 1 msec
;; SERVER: 127.0.1.1#53(127.0.1.1)
;; WHEN: Mon Aug 08 20:53:02 CEST 2016
;; MSG SIZE rcvd: 122
Again, the information we want is in the authority section. It seems to be the primary (ns1) nameserver of digitalocean.com. If you do not have access to the configuration of that DNS server, you will not be able to change the reverse IP lookup. Now, that doesn't mean you can't set it, because many hosters allow you to do that in their management interfaces. Alas, I can't help you there and you need to ask them, go read their FAQ, or explore the interface they have given you.
What I assume, but of course I may be wrong, is that you configured a DNS server on your localhost that is configured to reply the PTR records (reverse lookup), but the Internet at large will never query that machine, because... it's not authoritative.
So locally, it obviously works: your server "thinks" it's authoritative, but it's not.
Of course, I might be totally mistaken with my assumption.
Hope the reply is not all that confusing. DNS requires a quite deep understanding and the "authority" concept is very important.
