Reverse DNS (PTR record)

Reverse DNS associates an IP address with a hostname via a PTR record. It is essential for mail deliverability and trust in network tools (SMTP, monitoring, reverse WHOIS).

Prerequisites

• Dedicated IP on VPS, dedicated server, or dedicated mail egress at HolyCloud
• Domain you control (consistent A DNS zone)
• HolyCloud client area access to request or change PTR

On shared hosting, shared IP PTR is operator-managed; you mainly configure SPF/DKIM (see email docs).

Forward vs reverse DNS

| Direction | Record | Example |

|------|----------------|---------|

| Forward | A / AAAA | mail.votredomaine.fr → 203.0.113.10 |

| Reverse | PTR | 203.0.113.10 → mail.votredomaine.fr |

Both must be consistent (FCrDNS / « forward-confirmed reverse DNS ») for mail servers.

Check current PTR

dig -x 203.0.113.10 +short

or:

host 203.0.113.10

Typical response without client configuration:

ip10.holycloud.fr.

Choose PTR hostname

Best practices:

• Use a valid name: mail.votredomaine.fr, vps01.votredomaine.fr
• Avoid misleading generic names (localhost, third-party domain)
• One PTR per IP (multiple PTRs per IP discouraged)

Create matching A record:

mail.votredomaine.fr.  IN  A  203.0.113.10

Request PTR in HolyCloud client area

1. Log in to the client area.
2. VPS or Dedicated server → select the service.
3. IP / Network / Reverse DNS section (label varies).
4. Enter desired hostname (FQDN with trailing dot optional per UI).
5. Save — propagation often 15 minutes to 4 hours.

If the field is missing, open a ticket with:

• Concerned IP
• Requested PTR FQDN
• Justification (mail server, API, etc.)

Verification after change

dig -x 203.0.113.10 +short
dig mail.votredomaine.fr +short

Both commands should match:

# PTR
mail.votredomaine.fr.

# A
203.0.113.10

SMTP test (header excerpt): remote servers show pass on PTR checks if FCrDNS OK.

IPv6

Same principle with AAAA and PTR for 2001:db8:1234::2:

dig -x 2001:db8:1234::2 +short

Configure v6 PTR in the same network panel section if v6 is assigned.

Impact on mail deliverability

| Check | Without correct PTR |

|-------|------------------|

| Gmail / Outlook | Spam or rejection |

| Antispam score | Major penalty |

| Bounces | 550 5.7.25 or similar |

Combine PTR + SPF + DKIM + DMARC (hosting email documentation).

Multiple IPs and failover

• Each outbound mail IP needs its PTR (or a name consistent with active failover IP).
• After failover IP switch, update PTR if the public IP changes.

Troubleshooting

| Symptom | Action |

|----------|--------|

| PTR unchanged after 4 h | Ticket with IP; DNS cache — dig @8.8.8.8 -x IP |

| PTR points to wrong domain | Fix in panel; not at forward registrar |

| FCrDNS fail | PTR name A record does not match IP |

| Mail rejected despite PTR | Check SPF/DKIM, reputation, blacklists |

dig mail.votredomaine.fr +short
dig -x 203.0.113.10 +short

WHOIS and reputation

Some tools show PTR in IP reputation reports. A clear PTR (mail.votredomaine.fr) helps support during incidents.

Need help?

Ticket with IP, desired FQDN, current dig -x capture, and confirmation that the A record exists.