Technical
TTL (Time to Live)
A setting that controls how long DNS records are cached before being refreshed.
TTL (Time to Live) is specified in seconds and tells DNS servers how long to cache a record before checking for updates.
Common TTL Values:
- 300 (5 min): For records that change often
- 3600 (1 hour): Standard default
- 86400 (24 hours): For stable records
- 604800 (1 week): Maximum stability
TTL Trade-offs:
Low TTL (5-15 minutes): Pros:
- Fast propagation of changes
- Quick recovery from mistakes
Cons:
- More DNS queries (slower)
- Higher load on nameservers
High TTL (24+ hours): Pros:
- Fewer DNS queries (faster)
- Better performance
Cons:
- Slow propagation of changes
- Stuck with mistakes longer
Best Practice for Changes:
- Lower TTL to 300 at least 24 hours before planned changes
- Make your DNS changes
- Verify changes are working
- Raise TTL back to 3600 or higher
Why It Matters
Proper TTL management allows you to make DNS changes quickly when needed, while maintaining good performance during normal operation. It's a crucial tool for migrations and troubleshooting.
Practical Example
Before moving to a new web host, you lower your A record TTL to 300. After the move, DNS updates within minutes. Once stable, you raise TTL to 3600 for better performance.
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