TTL (Time To Live) is a value that determines how long specific data, such as DNS records or network packets, can be stored in cache before being refreshed or discarded. TTL is primarily used in DNS (Domain Name System) but also applies to IP networking, HTTP caching, and web performance optimization.
How Does TTL Work in DNS?
In the DNS system, TTL defines how long DNS servers or Internet Service Providers (ISPs) can store domain information in their cache before querying the authoritative DNS server again.
- Lower TTL (e.g., 300 seconds = 5 minutes) – Changes propagate faster, but DNS servers must query more often, slightly increasing latency.
- Higher TTL (e.g., 86400 seconds = 24 hours) – Reduces server load but delays DNS updates.
Common TTL Values for DNS Records
| DNS Record | Recommended TTL | Usage |
|---|---|---|
| A Record (IPv4) | 300 – 3600 s | Maps domain to an IP address |
| CNAME Record | 3600 – 86400 s | Alias for another domain |
| MX Record (Mail Exchange) | 3600 – 86400 s | Email server settings |
| TXT Record (SPF, DKIM) | 3600 – 86400 s | Email authentication and security |
| NS Record (Nameserver) | 86400 s | Domain name servers |
How to Check and Modify TTL?
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Check TTL Using Command Line Tools
- On Windows, open cmd and enter:
nslookup -debug yourdomain.com - On Linux/macOS, use:
dig yourdomain.com
- On Windows, open cmd and enter:
-
Change TTL in Your DNS Provider’s Control Panel
- Log in to your domain registrar (e.g., GoDaddy, Namecheap, Cloudflare, Google Domains).
- Navigate to DNS settings and modify the TTL values for specific records.
TTL in Network Protocols
Besides DNS, TTL is used in various networking technologies:
- IP Packets (Internet Protocol) – TTL limits how long a packet can travel in the network before being discarded.
- HTTP Cache – TTL determines how long static files (images, scripts, stylesheets) can be stored in a browser’s cache, improving website speed.
Best TTL Settings for Different Use Cases
- For frequent updates (e.g., website migration, testing): TTL 300 – 600 s.
- For normal websites with occasional changes: TTL 3600 – 14400 s.
- For stable records (e.g., MX, NS): TTL 86400 s (24 hours).
TTL (Time To Live) is a critical setting in DNS and networking that affects record update speed and server performance. Lower TTL enables faster changes, while higher TTL reduces DNS query load. Optimizing TTL settings ensures better website availability and performance.
