DNS Configuration

DNS configuration involves managing the records that translate human-readable domain names into IP addresses and other infrastructure endpoints. Proper DNS setup is fundamental to web application deployment, affecting availability, performance, email deliverability, and security. Key record types include A (IPv4 address), AAAA (IPv6 address), CNAME (canonical name alias), MX (mail exchange), TXT (verification and policy data), NS (nameserver delegation), and SRV (service location).

Modern DNS configuration extends beyond basic name resolution. TXT records are used for SPF (email sender policy), DKIM (email signing), DMARC (email authentication policy), and domain ownership verification for third-party services. CAA records restrict which Certificate Authorities can issue certificates for a domain. DNS-based load balancing uses multiple A records or weighted routing policies, while geo-DNS routes users to the nearest server. ALIAS or ANAME records (provider-specific) enable CNAME-like behavior at the zone apex.

Operational considerations include setting appropriate TTL values (low TTLs before migrations for fast propagation, higher TTLs in steady state for caching), using DNS providers with Anycast networks for low-latency resolution, configuring DNSSEC for response authentication, monitoring DNS propagation after changes, and maintaining an audit trail of record changes. Infrastructure-as-code tools like Terraform or Pulumi can manage DNS records declaratively alongside other infrastructure.