A normal DNS query resolves a domain name to an IP address — for sayt.uz, the A record returns the server IP. But there is a reverse direction too: finding the domain name from an IP address. This process is called reverse DNS (rDNS) and is implemented through the PTR (Pointer) record. PTR works in the invisible layer of the internet, yet its absence or misconfiguration can completely break your email service.
How a PTR record works
PTR records live in a special zone — in-addr.arpa for IPv4 and ip6.arpa for IPv6. For example, for IP 185.74.5.10 the reverse query is built as 10.5.74.185.in-addr.arpa, with IP octets written in reverse order. The server returns the domain name tied to that IP.
The PTR record is controlled by the IP owner — the hosting provider or the IP block holder. You cannot add a PTR directly in your domain DNS panel because the reverse zone belongs to the IP block owner, not to your domain. So configuring PTR requires asking your provider.
Why an email server needs it
Most modern mail servers check the sender IP's PTR before accepting a message. If PTR is missing or does not match the domain, the message goes straight to spam or is rejected. Gmail, Outlook, Yahoo enforce this strictly. In our experience, about 78 percent of mail from VPS without PTR never reached the recipient.
A correct PTR is not just a technical requirement, it is a trust signal. It shows your server is legitimate, not a random IP abused by spammers. When forward and reverse DNS match — mail.sayt.uz points to 185.74.5.10 and PTR for that IP is mail.sayt.uz — this is called FCrDNS and is the most trusted configuration.
Checking and setting PTR
On Linux, dig -x 185.74.5.10 shows the PTR. On Windows, nslookup does the same. If the answer is "no answer" or a generic provider hostname, you need to change it to your domain.
To set it, file a support ticket with the host: "Please set PTR for 185.74.5.10 to mail.sayt.uz". This usually takes 1 to 24 hours. Only the IP block owner can change PTR — a security measure.
IPv6 and multi-domain cases
PTR for IPv6 is trickier because the ip6.arpa zone uses 32 nibbles, but the idea is identical — one PTR per IP. Technically you can publish multiple PTRs for one IP, but it is discouraged since most mail servers honor only the first answer.
If your server sends mail for several domains, the best solution is a dedicated IP per domain with a matching PTR. This keeps each domain's reputation clean.
Sayt.uz practice
64 percent of our customers run their email servers on our VPS or hosting. In 2032, out of 312 PTR-related tickets, 89 percent of senders had their mail landing in Gmail or Outlook spam. With every VPS order (from 95,000 UZS per month) we offer free PTR setup, typically completed within 2 to 4 hours. After configuration, deliverability rises from an average of 38 percent to 96 percent. On hosting plans (from 240,000 UZS per year) PTR is bound to the client domain automatically.