DNS Propagation Guide
Reference common DNS propagation, caching, resolver, nameserver, and cutover terms.
DNS propagation is mostly cache expiration. Existing cached records can remain visible until their TTL expires.
| Term | What It Means | Typical Impact | Example |
|---|---|---|---|
| DNS Propagation | The time it takes DNS changes to be seen across recursive resolvers and caches globally. | Minutes to 48 hours | Updating example.com to point to a new server |
| TTL | Time To Live. How long DNS resolvers are allowed to cache a DNS record. | Lower TTL = faster changes after cache expires | 300 seconds = 5 minutes |
| Authoritative Nameserver | The DNS server that holds the source-of-truth records for a domain. | Must be updated for DNS changes to take effect | Cloudflare, Route 53, GoDaddy DNS |
| Recursive Resolver | A DNS resolver that looks up and caches DNS answers for users. | May serve old cached records until TTL expires | Google DNS, Cloudflare DNS, ISP DNS |
| DNS Cache | Stored DNS lookup result used to avoid repeated lookups. | Can delay visible changes | Browser cache, OS cache, resolver cache |
| Registrar | Company where the domain is registered. | Controls nameserver settings | Namecheap, GoDaddy, Cloudflare Registrar |
| Registry | Organization that manages a TLD. | Updates nameserver delegation for domains | .com, .net, .org registry |
| Nameserver Change | Updating which DNS provider controls the domain’s DNS zone. | Usually slower than record changes | Moving DNS from GoDaddy to Cloudflare |
| Record Change | Updating an existing DNS record inside the same DNS provider. | Usually faster than nameserver changes | Changing an A record IP |
| New Record | Adding a DNS record that did not previously exist. | Often visible quickly because there may be no old cache | Adding api.example.com |
| Negative Cache | Cache of a failed DNS lookup, such as a record not existing. | Can delay new records from appearing | blog.example.com previously returned NXDOMAIN |
| A Record | Points a hostname to an IPv4 address. | Website/server routing | example.com → 192.0.2.10 |
| AAAA Record | Points a hostname to an IPv6 address. | IPv6 website/server routing | example.com → 2001:db8::1 |
| CNAME Record | Points one hostname to another hostname. | Alias routing | www.example.com → example.com |
| MX Record | Defines mail servers for a domain. | Email delivery | example.com → mail.example.com |
| TXT Record | Stores text values for verification, email auth, and configs. | Verification/security | SPF, DKIM, DMARC |
| NS Record | Defines authoritative nameservers for a domain or subdomain. | DNS delegation | example.com → ns1.provider.com |
| SOA Record | Stores zone metadata, including negative caching TTL. | Affects DNS behavior and caching | Start of Authority record |
| DNSSEC | Adds cryptographic validation to DNS responses. | Misconfiguration can break lookups | DNSSEC enabled with incorrect DS record |
| DS Record | DNSSEC record stored at the registrar/registry level. | Must match DNS provider’s DNSSEC settings | Delegation Signer record |
| Local DNS Cache | Cache stored on the user’s device or network. | May show stale results locally | macOS DNS cache, router cache |
| Browser DNS Cache | DNS cache stored by the browser. | Browser may show old destination | Chrome, Firefox, Safari cache |
| ISP Cache | Cache maintained by the user’s internet provider. | Can lag behind public DNS resolvers | Comcast, AT&T, Spectrum |
| Public DNS Resolver | Public recursive DNS service. | Useful for testing propagation | 8.8.8.8, 1.1.1.1, 9.9.9.9 |
| Cache Flush | Clearing stored DNS results. | Can force a fresh lookup locally | Flush OS/browser DNS cache |
| Split-Horizon DNS | Different DNS answers depending on network/location. | Can make propagation look inconsistent | Internal vs external DNS |
| GeoDNS | DNS answers vary by geographic location. | Different regions may see different IPs | US users get one IP, EU users another |
| Anycast DNS | Same DNS IP served from multiple global locations. | Improves DNS speed and resilience | Cloudflare DNS, Google DNS |
| Root DNS | Top-level DNS infrastructure that points to TLD nameservers. | Rarely involved directly in simple record changes | Root zone lookup |
| TLD Nameserver | DNS server for a domain extension. | Points to domain authoritative nameservers | .com nameservers |
| Zone File | Collection of DNS records for a domain. | Holds the DNS configuration | All records for example.com |
| Zone Transfer | Copying DNS zone data between servers. | Used by DNS infrastructure, not typical users | AXFR transfer |
| Propagation Checker | Tool that queries DNS from multiple locations/resolvers. | Helps compare global DNS visibility | DNSChecker, whatsmydns |
| Dig | Command-line DNS lookup tool. | Best for checking exact DNS answers | dig example.com A |
| Nslookup | Command-line DNS lookup tool. | Simple DNS troubleshooting | nslookup example.com |
| Stale Record | Old DNS value still being returned from cache. | Causes users to hit old server/service | Old IP still resolving |
| Fresh Record | Current DNS value returned from authoritative DNS or expired cache. | Desired result after change | New IP resolving |
| Full Propagation | Most or all resolvers return the new DNS value. | Change appears globally complete | All checks show new value |
| Partial Propagation | Some resolvers return old value and others return new value. | Normal during DNS transition | Some users see old site |
| Rollback | Reverting DNS records to a previous value. | Also subject to TTL/cache delay | Restore old A record |
| DNS Cutover | Switching traffic from one target to another using DNS. | Needs TTL planning | Migrating hosting providers |
| Pre-Lowering TTL | Lowering TTL before a planned DNS change. | Helps speed up later cutover | Change TTL from 3600 to 300 beforehand |
| Grace Period | Time after DNS change when both old and new systems should work. | Prevents downtime during propagation | Keep old server online for 24 to 48 hours |