Understanding DNS Records
What Are DNS Records?
DNS (Domain Name System) records are instructions stored on DNS servers that tell the internet how to handle requests for a domain. They translate human-readable domain names into IP addresses and specify where emails should be delivered, which servers to use, and more.
Each record type serves a specific purpose: A records point to IPv4 addresses, AAAA records point to IPv6 addresses, MX records handle email routing, and TXT records store various text-based information including security policies.
Why Check DNS Records?
Checking DNS records helps troubleshoot connectivity issues, verify email configuration, confirm security settings, and understand how a domain is set up. It's essential for website migrations, email deliverability issues, and security audits.
Developers and system administrators regularly check DNS records to ensure proper configuration, diagnose propagation delays after changes, and verify that security measures like SPF, DKIM, and DMARC are correctly implemented.
TTL and DNS Propagation
TTL (Time To Live) determines how long DNS resolvers cache a record before checking for updates. Lower TTL values mean faster propagation of changes but more DNS queries. Higher values reduce server load but delay updates.
When making DNS changes, consider lowering TTL values beforehand to speed up propagation. After changes are complete, you can increase TTL again. Common TTL values range from 300 seconds (5 minutes) to 86400 seconds (24 hours).
Security and DNS
DNS plays a crucial role in email security. TXT records often contain SPF policies that specify authorized mail servers, DKIM signatures for email authentication, and DMARC policies for handling failed authentication.
CAA (Certificate Authority Authorization) records specify which certificate authorities can issue SSL certificates for your domain, adding an extra layer of security against unauthorized certificate issuance.