DNS TTL best practices 🧠
A Simple Guide to Time-To-Live in DNS
DNS TTL (Time-To-Live) is one of the most overlooked, yet essential, settings in your domain’s DNS configuration. It plays a critical role in how quickly DNS changes propagate and how efficiently your website performs across the internet.
In this article, we’ll explain what DNS TTL is, DNS TTL best practices, how it works, and how to use it effectively in real-world scenarios.
🔍 What is DNS TTL?
TTL (Time-To-Live) is a value in seconds that tells DNS resolvers (like your browser or ISP) how long they should cache a DNS record before checking for an updated version.
Example:
If your TTL is set to 3600 seconds (1 hour), any DNS resolver that looks up your domain will remember the IP address or other record for 1 hour before asking the authoritative DNS server again.
⚙️ How Does TTL Work in DNS?
When someone visits your website:
- Their DNS resolver queries your DNS provider.
- The response (IP address, CNAME, etc.) is cached.
- TTL controls how long this cached response is kept before being refreshed.
This helps reduce DNS traffic and speeds up website access, but it also affects how fast changes to DNS records (like IP address updates) take effect.
🧪 Practical Use Cases for TTL
Standard Website Hosting
- Recommended TTL: 3600 (1 hour)
- Why: Balances performance and flexibility. Most content doesn’t change IPs often.
Email (MX Records)
- Recommended TTL: 86400 (24 hours)
- Why: Email delivery systems don’t change frequently, so longer caching is fine.
CDNs & Load Balancers
- Recommended TTL: 300 (5 minutes) or less
- Why: IPs may change dynamically; shorter TTL ensures fast propagation.
DNS Migration or Record Change
- Before migration: Lower TTL to 60–300 seconds (1–5 min) 24–48 hours before change.
- After migration: Increase TTL back to reduce DNS query load.
Internal or Dev Environments
- TTL: Often set to 60 for rapid testing and changes.
📊 Pros and Cons of Short vs Long TTLs
| TTL Type | Pros | Cons |
|---|---|---|
| Short (<300s) | Fast propagation of changes | Higher DNS traffic and cost |
| Long (>3600s) | Better performance and lower load | Slow to update in case of issues |
✅ Best Practices for Managing DNS TTL
- Plan ahead: Lower TTL days before making DNS changes.
- Balance load: Use longer TTLs to reduce server queries.
- Monitor uptime: Short TTLs can help reroute traffic faster during outages.
- Use provider defaults wisely: Many DNS providers default to 3600—a good general value.
🧩 Where to Set TTL?
TTL is typically set when you create or edit a DNS record. Most domain registrars and hosting providers allow you to adjust this in their DNS management dashboard.
Look for:
- A column labeled TTL when managing A, AAAA, CNAME, MX, or TXT records.
- A dropdown or manual input field to adjust the TTL in seconds.
🔑 Conclusion: Why DNS TTL Matters
DNS TTL controls how long your DNS records are cached, directly affecting your website’s performance, reliability, and agility during changes. Choosing the right TTL for your needs ensures faster DNS propagation during updates and optimized user experience for visitors.
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