What is TTL time

How does an TTL  work

TTL works by setting a timer for how long DNS servers can store a record in their cache before refreshing it. When a user queries your domain, their device contacts a DNS server to get the necessary records. If the server already has the record in its cache and the TTL has not expired, it uses the cached information. If the TTL has expired, the server fetches the updated record from the authoritative DNS server.

Shorter TTL values ensure that changes to DNS records, such as updating an IP address, propagate faster across the internet. Longer TTL values reduce the frequency of queries to authoritative servers, improving efficiency and reducing server load.

The choice of TTL depends on the balance between update speed and caching efficiency.

Understanding key components

TTL is a straightforward concept, but understanding its components helps in setting it correctly.

• Time to Live Value: This is the duration in seconds that a DNS record is cached. Common TTL values are 300 (5 minutes), 3600 (1 hour), or 86400 (1 day). The value you choose depends on how quickly you might need to update your records.
• ‍DNS Record Types: TTL applies to all DNS record types, including A, MX, CNAME, TXT, and others. Each record can have its own TTL, allowing flexibility in managing updates for different services.‍
• Caching Behavior: TTL controls how long DNS resolvers, such as ISP servers or browser caches, store the records before checking for updates. It affects how quickly changes to your DNS records are reflected globally.

Examples

TTL settings impact various aspects of domain management and user experience.

• If you are launching a new website and need to switch hosting providers, setting a shorter TTL (e.g., 300 seconds) for your A records ensures the transition happens quickly. This minimizes downtime and ensures users see the updated site sooner.
• For email servers, a longer TTL for MX records (e.g., 86400 seconds) reduces the frequency of DNS lookups. This improves efficiency without affecting reliability, as email server configurations rarely change.
• If you’re managing a temporary promotion on a subdomain, such as “promo.mybusiness.com,” setting a short TTL allows you to make rapid updates to the DNS records if the target server changes.

These examples show how TTL settings can be adjusted based on the specific needs of your domain.

How to check your TTL

Checking your TTL settings is important for ensuring that your DNS records behave as expected. Start by logging into your domain registrar or DNS hosting provider. Navigate to the DNS management section, where all your domain’s records are listed.

In the list of DNS records, each entry will include a TTL value. Verify that the TTL matches your requirements for update speed and caching efficiency.

You can also use external tools like MXToolbox or command-line utilities like dig to query your domain’s DNS records.

Common problems and how to fix them

Incorrect or poorly configured TTL settings can lead to issues with your domain’s performance and accessibility. Understanding and fixing these problems is crucial for maintaining a reliable online presence.

• Too Long TTL: If the TTL is set too long, changes to your DNS records will take longer to propagate. Use shorter TTL values during periods of frequent updates, such as a website migration or DNS changes.
• ‍Too Short TTL: If the TTL is too short, DNS servers will frequently query authoritative servers, increasing server load and potentially slowing down DNS resolution. Use longer TTL values for stable records like MX or TXT.‍
• Propagation Delays: Changes to TTL settings themselves may take time to propagate. Plan updates carefully and verify them after the propagation period.‍
• Inconsistent TTL Values: Having inconsistent TTL values across related DNS records can cause confusion and delays in resolution. Ensure that TTL values are uniform where consistency is required.