Question 1

What is DNS propagation?

Accepted Answer

DNS propagation is the process of updating DNS records across all resolvers worldwide after a change is made. When you update a DNS record, the change starts at authoritative nameservers and gradually spreads to cached resolvers globally. This can take anywhere from minutes to 48 hours depending on TTL values.

Question 2

Why do some locations see different DNS results?

Accepted Answer

DNS resolvers cache records based on TTL (Time To Live) values. If a resolver has cached the old record, it will serve that until the TTL expires. Different ISPs and resolver networks have different update schedules, causing geographic inconsistency during propagation.

Question 3

How long does DNS propagation take?

Accepted Answer

Propagation time depends on the TTL set on the old record. A TTL of 3600 seconds (1 hour) means resolvers may hold the old value for up to an hour. Lower TTLs (300s) speed up propagation. For urgent changes, lower your TTL 24-48 hours before making the change.

Question 4

Why is my DNS change not propagating?

Accepted Answer

Common reasons: high TTL on old records, ISP-level caching (some ISPs ignore TTL), misconfigured authoritative nameservers, or propagation is still in progress. Check that your authoritative nameservers are serving the correct records first using nslookup or dig.

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