A name needs an address
A client asks a recursive resolver for the address behind a hostname. Cached records can answer immediately while their cache lifetime remains valid.
DNS resolution
How a domain name resolves to an IP address.
Process overview
- Resolve
- Root
- TLD
- Authority
- Return
Steps
5 stepsThe root points to the right suffix
On an uncached lookup, the resolver asks a root nameserver. The root refers it to the nameservers for the top level domain.
The suffix points to the domain
A top level domain nameserver, such as one for .com, returns a referral to the domain’s authoritative nameservers.
The authoritative server answers
The authoritative nameserver returns the requested record. An A or AAAA record provides an IP address; aliases can require another lookup.
The address reaches the client
The resolver returns the answer and can cache it. The client now has addressing information it can use to connect to the site.
Keyboard: ←→
Scope
A simplified uncached DNS lookup. Caching, aliases, delegation, and DNS security can change the path.
