Reverse DNS Lookup
Find the hostname behind an IP address from its PTR record, and check whether that hostname resolves back to the same IP (forward-confirmed reverse DNS). Enter a public IPv4 or IPv6 address such as 8.8.8.8.
- Free
- No signup required
- Live DNS lookup
Common reverse DNS problems
No PTR record for your mail server
Many receivers, including Gmail, expect a sending IP to have a PTR record and may reject or spam-folder mail without one. Ask whoever owns the IP to set it: your hosting or cloud provider, not your domain's DNS host.
PTR does not resolve back to the same IP
The PTR says mail.example.com, but mail.example.com has no A record or points elsewhere. Receivers check both directions, so add or fix the A (or AAAA) record so the name resolves to this IP.
Generic PTR from the provider
Names like ec2-203-0-113-10.compute-1.amazonaws.com or a string of digits from an ISP look like dynamic or unmanaged addresses to spam filters. For a mail server, set a PTR that names your own host, such as mail.example.com.
You added a PTR at your DNS provider and nothing changed
Reverse zones belong to the owner of the IP block. A PTR record in your example.com zone does nothing. Use the reverse DNS setting in your provider's panel (AWS Elastic IP, Hetzner, DigitalOcean droplet name, Linode) or open a ticket with them.
Private IP addresses
Addresses such as 10.x, 172.16-31.x and 192.168.x only have reverse DNS inside their own network, so this tool refuses them. Check them from a machine on that network instead.
How to do a reverse DNS lookup
- Enter a public IPv4 or IPv6 address, for example 8.8.8.8.
- Click Look up PTR.
- Read the PTR hostname and whether it resolves back to the same IP.
- If it does not match, fix the A record for the name or ask the IP owner to change the PTR.
What is reverse DNS?
Normal DNS turns a name into an IP address. Reverse DNS does the opposite: it turns an IP address into a name, using a PTR (pointer) record.
PTR records live in special zones. For IPv4, the address is reversed and placed under in-addr.arpa, so 203.0.113.10 becomes 10.113.0.203.in-addr.arpa. IPv6 uses ip6.arpa with each hex digit reversed. These zones are run by whoever owns the IP block, usually your ISP, host or cloud provider, which is why you set PTR records in their panel and not in your own domain's DNS.
Forward-confirmed reverse DNS means the PTR name also resolves back to the same IP. Mail servers check this as a basic sign that a sending server is set up deliberately. It does not prove a message is legitimate, but missing or mismatched reverse DNS is a common reason for rejected mail.
Outside email, reverse DNS makes logs and traceroutes readable and often shows which provider runs an address.
10.113.0.203.in-addr.arpa. 3600 IN PTR mail.example.com. mail.example.com. 3600 IN A 203.0.113.10
When to use a reverse DNS lookup
Setting up a mail server on a VPS
Before sending from a server on AWS, Hetzner or DigitalOcean, confirm the PTR names your mail host and resolves back to the same IP.
Investigating rejected email
If bounces mention reverse DNS or PTR, check the sending IP here to see whether the record is missing or does not match.
Identifying an IP in your logs
See which provider or network an address in your nginx or firewall logs belongs to.
Checking a new dedicated IP
When a provider such as SendGrid or Mailgun assigns you a dedicated IP, confirm its reverse DNS is set to the expected name.
Check something else
- Domain to IP LookupFind the IP addresses behind a domain: A and AAAA records with TTLs, the CNAME chain and reverse DNS.
- MX LookupFind the mail servers for a domain, in priority order, with TTLs and each server's IP addresses.
- Email Health CheckScore a domain's email setup: MX, SPF, DMARC, DKIM and MTA-STS, with the issues to fix first.
- Port CheckerCheck if a TCP port is open, closed or filtered on a host, with the connect time.
Frequently asked questions
Who sets the PTR record for my IP?
The owner of the IP block: your hosting company, cloud provider or ISP. Most cloud panels have a reverse DNS field; otherwise ask support. Adding a PTR in your own domain's zone has no effect.
Do I need reverse DNS for my website?
Not for serving web pages. Browsers never check it. It matters for servers that send email, and it helps when reading logs.
What is forward-confirmed reverse DNS?
The IP's PTR gives a hostname, and that hostname's A or AAAA record includes the same IP. Mail receivers check this match, and many treat a mismatch as a sign of a badly configured or compromised sender.
Can an IP have more than one PTR record?
It is allowed, but not recommended. Software often reads only the first answer, so set one PTR per IP that names the main host.
Why can I not look up private IPs?
Private ranges such as 192.168.x.x are not unique on the internet and their reverse zones are only answered inside each network. Public resolvers have nothing meaningful to return for them.
Stop checking your servers by hand
A mail or web server can stop answering without anyone noticing until messages bounce. TinyPing watches a port or pings the server every 5 minutes and alerts you when:
- the port stops accepting connections
- the server stops answering
- it comes back, with a recovery alert
US$6.99 a month or US$47 a year per 50 monitors, team members free. 7-day free trial, no card needed.
Want alerts in team chat? Follow the guide for Slack or Google Chat.