A PoinTeR or PTR record is an A record in reverse: it associates server IP with a domain name. A PTR could be used:
Note: A PTR record can be added only in the reverse DNS zone (RDNS) and not in a regular domain zone. Therefore, in the Gcore UI, there is no PTR record in the list of resource records that can be added for a forward domain zone.
A reverse DNS lookup is a special zone that is intended to define the hostname by its IPv4 or IPv6 address using a PTR record.
Note: You can add a PTR record to a reverse lookup zone only if your zone is under the top-level domain (TLD)
in-addr.arpa (for IPv4) or
ip6.arpa (for IPv6). After creating a zone under the TLD, you can then create a PTR record in the UI.
An IPv4 host address AAA.BBB.CCC.DDD in the reverse DNS zone is represented in the format: DDD.CCC.BBB.AAA.in-addr.arpa. For example, a Gcore site address 220.127.116.11 in a reverse DNS query would be 18.104.22.168.in-addr.arpa.
And the IPv6 in a reverse DNS lookup will work the same way, but with a slight difference. For example, the address 2a03:90c0:501:2801::62 will be rendered as 22.214.171.124.126.96.36.199.5.0.c.0.9.3.0.a.2.ip6.arpa in the reverse DNS zone.
You need to have a dedicated IP space (IPv4 or IPv6) to configure the reverse DNS zone. Here’s how to do it:
1. Contact an organization with RIR status (that is, a technical registrar authorized to create and delegate reverse DNS zones) and ask them to delegate the zone of your subnet to Gcore NSs.
2. When you get a reverse DNS zone, add it in the Gcore control panel according to our guide Create a DNS zone. Note: You can add a subnet up to /24 bits for your IP address.
3. Open the added reverse zone xx.xx.xx.in-addr-arpa in the control panel and add the PTR records you need.
4. Specify Gcore’s name servers ns1.gcorelabs.net and ns2.gcdn.services for the subnet xx.xx.xx/24 and wait up to 24 hours for DNS cache updating.
That’s it! The PTR record is now added and will prevent your mail from ending up as spam.
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