I assumed I would set up a PTR record with my other DNS records, but have been told by my hosting company that "a PTR record should be set up at the side of your server, not as a DNS record in your domain zone file." But I can't find any explanation, anywhere, for how to do this.
It's a Linux server.
This is something that only your hosting provider can do. Maybe they offer this functionality in some kind of management menu, but this should be documented or their support should be able to walk you through the process. Ask them, we can't help you further.
Only your hosting Provider can set PTR record for you For e.g if you have vps with ip: 1.2.3.4 even if you set ptr in your dns record it will not change. only the owner of ip 1.2.3.4 which rented you the vps with this ip is able to set ptr record pointing to your domain therefor you need to contact your Hosting Provider and ask them to do it for you. some providers create a feature to set ptr record from admin panel.
Some confusing answers here already.
Only the party controlling the IP address can serve up the authoritative PTR record.
However it is possible that your hosting provider has configured their DNS service to proxy PTR requests. This is a somewhat uncommon, but elegant solution to the provisioning problem. Alternatively they may be delegating the PTR record to your server.
It's a Linux server.
hmmm.
This paints a picture of your level experience, if not one of the technical reality.
If my guesses about your hosting provider are correct then in order to achieve this you need to:
Find out whether your DNS provider is delegating or proxying the PTR lookups.
If they are delegating the access, AND YOU REQUIRE PTR records, go learn about firewalls, amplification attacks, DNS poisoning....or hire a professional to configure this
If they are proxying access, then find out from which address, configure the firewall on the host to block DNS requests from ANY OTHER address (on tcp and udp) provision a DNS server with ACLS which ONLY allow access from the DNS proxy address
However there only a few cases where a PTR record is actually required to make stuff work - and these are all highly technical. You didn't say why you needed PTR records. If you do not require PTR records then do not try to provision this.
Often ISPs and hosting companies allow you to setup a reverse DNS record either on a service web page of theirs or via a managed request. Your mileage may vary.
As an option, a PTR record for a single IP address can be delegated to another DNS server so the server admin can update it himself.
All this said, if your IP address 1.2.3.4 and you have a DNS A record pointing to it like www.mydomain.tld, a minimal PTR record would look like this:
4.3.2.1.in-addr.arpa. IN PTR www.mydomain.tld.
Please, note how the IP address octets are reversed in the left part of the record and also note the trailing domain name in-addr.arpa..
Also, be very careful with the trailing dots: the DNS won't forgive you! We never use trailing dots but the DNS cannot leave without: it's part of the delegation tree.
For other technical details you can refer to the latest RFC.
Take after strides to Create the PTR record
A basic clarification of invert DNS is that it's the correct inverse of DNS. Standard (otherwise known as forward) DNS maps a space name to an IP address while invert DNS maps an IP deliver to an area name. The two are unmistakable and isolate queries in any case. Because a forward query of example.com sets out to 1.2.3.4 doesn't imply that a turn around query of 1.2.3.4 will take steps to example.com.
