Generate Correct DNS Zone Files

This skill creates, manages, and optimizes DNS zone files in BIND syntax, covering DNS record types, zone file structure, and best practices for generating complete, syntactically correct zone files for any domain configuration. Core structural principles: start with an SOA (Start of Authority) record holding administrative info, set TTL values by expected change frequency, use consistent formatting and indentation, always include proper NS records, and terminate FQDN records with a trailing period to avoid relative-name interpretation. Record types covered: A/AAAA (IPv4/IPv6 mapping), CNAME (aliases, which cannot coexist with other record types on the same name), MX (mail exchange with priority), TXT (verification, SPF, DKIM, DMARC), SRV (service location with priority/weight/port), NS (delegation), and PTR (reverse lookups).

Use it when a domain's DNS needs a complete, correctly-formatted zone file - forward or reverse - rather than a handful of ad hoc records added one at a time.

$TTL 86400
$ORIGIN example.com.

@   IN  SOA ns1.example.com. admin.example.com. (
            2024010101  ; Serial (YYYYMMDDNN)
            7200        ; Refresh (2 hours)
            3600        ; Retry (1 hour)
            604800      ; Expire (1 week)
            86400       ; Minimum TTL (1 day)
            )

@               IN  NS      ns1.example.com.
@               IN  A       192.168.1.100
@               IN  MX  10  mail.example.com.

Full worked examples cover a complete forward zone (SOA, NS, A, AAAA, CNAME, MX, TXT, SRV records together) and a reverse zone under in-addr.arpa. with PTR records. TTL strategy pairs longer default TTLs for static infrastructure with short, per-record TTL overrides for dynamic entries (a 300s TTL for an API endpoint, 600s for a CDN). Email security is covered with SPF, DMARC (with rua/ruf reporting addresses and a fo=1 failure option), DKIM selector records, and MTA-STS policy records. Service discovery uses SRV records in _service._protocol priority weight port target format for protocols like SIP, CalDAV, and CardDAV. Common patterns include round-robin and geographic load balancing via multiple A records, and subdomain delegation with NS records plus glue A records for the delegated name servers. Validation guidance covers FQDN period termination, consistent spacing, numeric MX priorities, correct SRV field order, and serial-number conventions (date-based YYYYMMDDNN or Unix timestamp) that must always increment on change to trigger proper zone transfer and propagation.

Network and infrastructure engineers who need a complete, syntactically valid BIND zone file - forward or reverse, with mail security records and service discovery - rather than hand-assembling individual DNS records.