$TTL 86400 ; 24 hours, could have been written as 24h or 1d $ORIGIN example.com. @ 7d IN SOA ns1.example.com. hostmaster.example.com. ( 2017010101 ; serial 3H ; refresh 15 ; retry 1W ; expire 5m ; minimum ) ; name servers 7D IN NS ns1.example.com. ; in the domain 7D IN NS ns2.example.org. ; external to domain ; services and hosts ns1 IN A 192.168.0.1 ; name server IPv4 address ns1 IN AAAA 2001:0db8::1 ; name server IPv6 address www IN A 192.168.0.2 ; web server ftp IN CNAME www.example.com. ; ftp alias (absolute) xmpp IN CNAME www ; xmpp alias (relative) ; mail IN MX 10 mail.example.org. ; external mail provider mail._domainkey IN TXT "v=DKIM1\; h=sha256\; k=rsa\; s=email\; p=loooooooooog" ; CAA records for Let's Encrypt, one in RFC 3597 syntax IN CAA 0 issue "letsencrypt.org" ; IN CAA 0 iodef "mailto:abuse@example.com" IN TYPE257 \# 31 0005696F6465666D61696C746F3A6162757365406578616D706C652E636F6D ; xmpp _jabber._tcp IN SRV 5 0 5269 xmpp ; special xx.lcs.mit.edu. CH A mit.edu. 2420