The vocabulary of the DNS Propagation Checker API

The process by which DNS record changes spread across the global network of DNS servers and caches.

When you update a DNS record, the change must propagate from your authoritative nameservers to DNS resolvers worldwide. This process is controlled by TTL values and can take anywhere from minutes to 48 hours depending on caching configurations.

ExampleAfter changing your A record from 1.2.3.4 to 5.6.7.8, propagation is complete when DNS resolvers globally return the new IP address.

A value in seconds that specifies how long a DNS record should be cached before being refreshed.

TTL is set on each DNS record and tells resolvers how long to cache the record. Lower TTLs (300 seconds) allow faster propagation but increase DNS query load. Higher TTLs (86400 seconds) reduce queries but slow propagation. Typical values range from 5 minutes to 24 hours.

ExampleA TTL of 3600 means resolvers will cache the record for 1 hour before checking for updates.

A text file containing all DNS records for a domain, stored on authoritative nameservers.

Zone files define all records for a DNS zone (typically a domain). They include SOA records, NS records, A records, MX records, and more. When you edit DNS records through your provider's interface, you're updating the zone file. Zone transfers replicate this file to secondary nameservers.

ExampleA zone file for example.com contains A records for the apex domain and www subdomain, MX records for email, and TXT records for SPF.

A temporary storage of DNS query results used to speed up future lookups and reduce load on DNS servers.

DNS caches exist at multiple levels: browser cache, operating system cache, router cache, ISP resolver cache, and recursive resolver cache. Each level may cache records for the duration specified by TTL. During propagation, old cached records must expire before new records are fetched.

ExampleYour ISP's DNS resolver caches example.com's A record for 1 hour (based on TTL), so changes won't be visible to users on that ISP until the cache expires.

A DNS server that holds the original, definitive DNS records for a domain.

Authoritative nameservers are the source of truth for a domain's DNS records. When DNS changes are made, they're made on the authoritative nameservers. Recursive resolvers eventually query authoritative servers when their cache expires. Common authoritative DNS providers include Cloudflare, Route 53, and Google Cloud DNS.

Examplens1.example.com and ns2.example.com might be the authoritative nameservers for example.com, set at the domain registrar.

A server that receives DNS queries from clients and recursively resolves them by querying other DNS servers.

DNS resolvers (also called recursive resolvers) sit between users and authoritative nameservers. They cache results to speed up lookups. Popular public resolvers include Google (8.8.8.8), Cloudflare (1.1.1.1), and OpenDNS. ISPs also run resolvers for their customers.

ExampleWhen you type example.com in your browser, your configured DNS resolver (e.g., 8.8.8.8) handles the lookup, checking its cache first, then querying authoritative servers if needed.

A DNS record that specifies which servers are authoritative for a domain.

NS records delegate authority for a domain to specific nameservers. When you register a domain, you set NS records at your registrar pointing to your DNS provider's nameservers. Changing nameservers requires propagation like any other DNS change.

Exampleexample.com NS ns1.cloudflare.com indicates that Cloudflare's nameservers are authoritative for example.com.

A DNS record that maps a domain name to an IPv4 address.

A records are the most common DNS record type, used to direct traffic to web servers. When you change your hosting provider, you typically update A records to point to the new server's IP address. A domain can have multiple A records for load balancing.

Exampleexample.com A 93.184.216.34 means requests to example.com should be sent to IP address 93.184.216.34.

A DNS record that maps a domain name to an IPv6 address.

AAAA records serve the same purpose as A records but for IPv6 addresses. As IPv6 adoption grows, having both A and AAAA records ensures your domain is accessible to all users. AAAA records follow the same propagation rules as A records.

Exampleexample.com AAAA 2606:2800:220:1:248:1893:25c8:1946

A DNS query where the resolver fully resolves the domain name by querying multiple DNS servers on behalf of the client.

In a recursive query, the DNS resolver does all the work: it queries root servers, then TLD servers, then authoritative servers, caching results along the way. The client receives the final answer. This is how most DNS resolution works for end users.

ExampleYour browser asks 8.8.8.8 for example.com. Google's resolver recursively queries .com TLD servers, then example.com's nameservers, and returns the final IP to your browser.