Optimizing TTL for DNS Records for Improved Performance

When it comes to managing DNS records, one often overlooked yet critical setting is the TTL (Time to Live). In this updated and technical guide, we will explore TTL best practices and incorporate SEO considerations for DNS providers. By the end, you'll be equipped with the knowledge to optimize your DNS configurations and enhance your online presence. Plus, we'll wrap up with a compelling Call to Action (CTA) for DigiCert DNS Trust Manager.

Understanding TTL's Functionality

TTL determines how long DNS information should be cached by resolving name servers. Resolving name servers act as intermediaries in the DNS exchange process. When you enter a domain in your browser, your local resolving name server retrieves the corresponding IP address for that domain.

If someone has recently made a similar request, the resolving name server will likely have the information cached. Otherwise, it will query the authoritative name server responsible for the domain—often the DNS provider. Once the domain-to-IP mapping is found, the resolving name server stores the information, speeding up future resolution times for that domain.

Why TTL MattersWhile TTL times may not cause issues for basic A and CNAME records, they become crucial when dealing with dynamic endpoints like Failover. Consider a scenario where the primary IP address for a domain is unavailable, and Failover redirects users to a backup IP address.

Two Approaches to Handling Failover:

  1. High TTL: Users will continue to be directed to the primary IP address until the cache expires.
  2. Low TTL: Users have a higher chance of being pointed to the correct endpoint sooner.

Determining When to Use Short TTLs

  1. Dynamic Endpoint Rule: If you have rules that dynamically update endpoints, like Failover or Load Balancing, opt for a short TTL. Ask yourself, "How long am I comfortable with users reaching an unavailable endpoint before the cache refreshes?"
  2. Critical Records: Keep TTLs low (e.g., 30 seconds to 5 minutes) for important records.
  3. Record Changes: When making any modifications, set the TTL as low as possible. However, note that DigiCert DNS minimum TTL is 30 seconds, as most resolving name servers only consider TTLs of 30 seconds or higher.
  4. Advanced Settings: If you have advanced features like GeoDNS rules (e.g., with Constellix), choose a low TTL.
  5. Non-Critical Records with Future Changes: For records that are non-critical but may require changes in the near future, a short TTL is advisable. However, consider the trade-off between query costs and TTL duration. In this case, a TTL of 1 to 12 hours would be appropriate.

Opting for Long TTLsConsider cost and resolution times when deciding on longer TTLs:

  1. Records Requiring Long TTLs
  2. MX Record (points to your mail server)
  3. DKIM and SPF (usually configured with MX records)
  4. TXT Record
  5. Web Server and CDN Pointers (A and CNAME Records): These records are rarely modified, so longer TTLs (e.g., 12 hours to 1 day) are suitable. Remember to lower the TTL and wait until caches expire (usually around a day) before implementing changes.

Unlock the full potential of your DNS management with DigiCert DNS Trust Manager. Empower your organization with advanced features, streamlined workflows, and enhanced security. Discover how DigiCert DNS Trust Manager can optimize your DNS infrastructure and drive your online success.

Jessica Belvedere
Jessica is the Marketing Director for Constellix and DNS Made Easy. She likes quirky one-liners, SEO, and connecting with people.

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