Question
- What hostname should be set in the PTR (rDNS) record for an IP address that is used for email sending purposes on a Plesk server?
Answer
The IP addresses that are used on a Plesk server should always have PTR records that use the exact same value that is set in Plesk > Tools & Settings > Server Settings > Full hostname
PTR records for IP addresses can only be configured within the DNS zones of IP addresses.
Your server provider owns the IP addresses that are assigned to your Plesk server, due to which you need to contact it in order to find what you need to do in order to make the necessary PTR adjustments happen, because it is impossible to do that within Plesk or even the server itself.
Additional information
The following conventions are usually applied to PTR records:
- There should be exactly one PTR record per IP address/hostname pair. Each IP address should have a PTR record. Note that this isn’t one PTR record per computer, necessarily; a computer with multiple IP addresses would have multiple PTR records, one per address. If one address has multiple hostnames (real A-Records, not CNAME alias), there will be one PTR record per hostname/address pair.
- For any given MX record, the mailhost name used in the MX record must have an A record - this is the rule, not a convention. The convention is, that name’s IP address must have a PTR record that resolves back to the hostname used in the MX record.
- There should be an A record for every PTR record (but not necessarily vice versa). In other words, one should be able to take an IP address, look up its PTR record (yielding a hostname), and then look up the A record for that hostname and get back the IP address. The hostname should have exactly one A record (not a CNAME record).