People talk about DNS propagation as if records physically travel around the internet. That is not quite what happens. In most cases, propagation is caching: different resolvers keep old answers until their cached copy expires, then ask for the new answer.
The Short Version
When you change a DNS record, the authoritative DNS server has the new value immediately. The delay comes from other systems that already looked up the old value and are allowed to keep it for a period of time defined by the record's TTL.
What TTL Does
TTL means Time to Live. It tells resolvers how long they may cache a DNS answer. A shorter TTL can make planned changes easier, because resolvers are expected to come back for a fresh answer sooner. A longer TTL can reduce repeated lookups, but it also means old answers may remain in use for longer after a change.
Why Two People See Different Results
Two visitors can query different DNS resolvers. One resolver may still have the old answer cached. Another may have already refreshed and received the new answer. That is why a site can work on your phone but not your office connection, or work through one public resolver but not another.
Nameserver Changes Can Feel Slower
Changing nameservers affects where the DNS system goes to find the authoritative zone. This can involve cached delegation data as well as cached records. If you are moving nameservers, create all important records in the new zone before you switch.
How to Plan a Cleaner DNS Change
- Lower TTL ahead of a planned change if your provider allows it.
- Do not delete the old hosting immediately after switching DNS.
- Keep old email records copied into the new DNS zone.
- Use more than one DNS checker, but do not panic if they disagree for a while.
- Test from a normal browser, a mobile connection, and the command line if you can.
Useful Checks
For a website, check the A or CNAME record. For email, check MX and TXT records. For a subdomain, check the exact subdomain rather than the root domain. DNS is specific, and www.example.co.uk can point somewhere different from example.co.uk.
If you are moving a domain to TekLan and are unsure which records matter, open a support ticket. We can help you identify the records that need to be preserved.
