DNS Setting and Propagation

 DNS Settings & Propagation

What the DNS??

DNSs (Domain Name System) are the Internet's address book. When someone types yourdomain.ca into a browser, the DNS is what tells the internet, which server to go to. It is like your home address. When you have a friend coming to visit, it is the house number and street address name. 

 

A DNS is made up of records, each serving a specific purpose:

• A Record — Points your domain to an IP address (e.g., your website server).
• CNAME — Points one hostname to another (e.g., www → yourdomain.ca).
• MX Records — Tell the internet where to deliver email.
• TXT Records — Used for verification (Google, Microsoft, SPF, DKIM, DMARC).
• NS Records — Define which DNS provider is authoritative for your domain.

These records live on your DNS host (e.g., Namecheap, Cloudflare, GoDaddy).

 

Why DNS Changes Do not Update Immediately

        1. DNS Is Cached Everywhere

To keep the internet fast, DNS information is cached at multiple layers:

Your local device

Your router

Your ISP (Bell, Rogers, etc.)

Global DNS resolvers (Google DNS, Cloudflare DNS)

Browsers (Chrome, Edge, Firefox)

Each layer stores the old DNS answer until the cache expires.

 

        2. TTL Controls How Long Old Data Lives

Every DNS record has a TTL (Time To Live) value — usually 300 to 48,000 seconds (5 minutes to 48 hours).

Example: If your A record has a TTL of 3600 seconds, every resolver is allowed to keep the old IP for 1 hour before checking again.

Lower TTL = faster updates Higher TTL = slower updates

 

        3. Global Propagation Takes Time

When you update DNS:

Your DNS host updates instantly.

Some resolvers fetch the new data immediately.

Others continue using cached data until TTL expires.

Different regions update at different speeds.

This is why one person sees the new website while another still sees the old one.

Typical propagation time:5 minutes → 48 hours Most changes settle within 1–4 hours.

 

    4. Email‑Related Records Take Longer

SPF, DKIM, and DMARC often feel slower because:

Mail servers cache aggressively

Some providers only refresh every few hours

Email reputation systems may take 24–72 hours to adjust

 

How to Speed Up DNS Changes?

• Lower TTL 24 hours before making changes (e.g., set to 300 seconds).
• Make your DNS changes.
• Raise TTL again after everything is stable.
• If you didn’t lower TTL beforehand, you simply have to wait for caches to expire.

 
How to Check Propagation?

Use tools like:

• whatsmydns.net
• dnschecker.org
• dig (command line)