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Understanding DNS Propagation

When you update your domain's DNS records—whether you're changing your web host, updating an IP address, or setting up a new email service—the changes don't happen everywhere at once. This delay is known as DNS Propagation.

DNS Propagation

What is DNS Propagation?

DNS propagation is the timeframe required for the "phonebooks" of the internet (DNS nodes) to update their caches across the globe. Because the internet is a decentralized network, your new DNS settings must be broadcasted from your Authoritative Nameservers to every other server on the planet.

How it Works

graph LR
    A[You Change IP] -->|Update| B[Authoritative DNS]
    B -.->|TTL Expired| C[ISP Cache Node]
    B -.->|TTL Expired| D[Google DNS]
    C -->|Serves New IP| E[User in London]
    D -->|Serves New IP| F[User in New York]

    style A fill:#e6ffcc,stroke:#82b366,stroke-width:2px
    style B fill:#ffe6cc,stroke:#d79b00,stroke-width:2px
  1. The Change: You update a record (e.g., an A Record) in your hosting control panel.
  2. The Update: Your local DNS server updates immediately.
  3. The Spread: ISP (Internet Service Provider) nodes across the world begin checking for updates.
  4. The Cache: If a node has a "cached" version of your old record, it will continue to serve that until the record's TTL (Time to Live) expires.

Key Factors Influencing Speed

Several variables determine whether your site updates in 5 minutes or 48 hours.

Factor Description
TTL (Time to Live) The numerical value (in seconds) that tells a server how long to store a record before asking for a fresh one.
ISP Caching Some ISPs ignore TTL settings and refresh their DNS caches at their own scheduled intervals.
Registry Updates Changing your Nameservers (NS records) takes longer than changing a simple A or CNAME record, as it involves the Top-Level Domain (TLD) registry.

Pro Tip: Lower your TTL early

If you are planning a website migration, lower your TTL to 300 seconds (5 minutes) at least 24 hours before the move. This ensures that once you make the switch, the world sees the change almost instantly.

Read our Zero-Downtime Migration Guide

Why am I seeing the old site?

It is common for one person to see the new site while another sees the old one. This usually happens because:

  • Local Browser Cache: Your browser may be "remembering" the old IP address.
  • DNS Flush: Your computer's operating system has its own DNS cache.
  • Geographic Location: A DNS node in London might update faster than one in Sydney.

How to Clear Your Local Cache

To see the most recent version of your site, you can "flush" your DNS:

Open Command Prompt and type: ipconfig /flushdns

Open Terminal and type: sudo killall -HUP mDNSResponder

How to Track Progress

You can use online tools to see how your DNS records are performing across different global regions.

Wait for the full 48 hours

While many updates complete within a few hours, we recommend waiting a full 48 hours before troubleshooting a record that hasn't updated globally.

Summary

DNS propagation is the internet's way of updating its address book. It is normal for it to take up to 48 hours, but you can speed it up for yourself by flushing your local DNS.