DNS Resolver
Resolve domains to IP addresses or IP addresses to hostnames.
What does a DNS resolver do?
A DNS resolver converts domain names into IP addresses and can also perform reverse resolution from an IP address to a hostname. Resolution is one of the core functions of DNS because applications normally need an IP address before they can connect to an internet service.
Forward resolution uses DNS records such as A and AAAA. Reverse resolution works through PTR records stored in special reverse DNS zones. The two directions are related but are configured independently and do not always return matching results.
How to use the DNS Resolver
- Enter either a domain name or an IP address.
- Run the resolver.
- For a domain, review resolved IP addresses; for an IP, review the returned reverse DNS hostname or hostnames.
Understanding DNS resolution results
A domain can resolve to more than one address when services use load balancing, redundancy or a CDN. IPv4 addresses normally come from A records and IPv6 addresses from AAAA records.
A reverse result depends on whether the owner of the IP address has configured a PTR record. Missing reverse DNS is common and does not necessarily indicate a problem, although PTR records are important for some mail and infrastructure use cases.
Common uses for DNS resolution
- Resolve a hostname before testing a server connection.
- Find the hostname associated with an IP address.
- Compare forward and reverse DNS behavior.
- Troubleshoot unexpected DNS resolution.
- Check whether IPv4 and IPv6 addresses are both published.