Domain Name System (DNS)

See also: Active Directory#DNS, dnsmasq

• no-ip.com

Find out with namebench.

Format: <name> [<ttl>] [<class>] <type> <rdata>

https://de.wikipedia.org/wiki/SRV_Resource_Record

_service._proto.name. TTL class SRV priority weight port target.

Send mail from MX and A entries, prohibit all others:

example.com 28800 TXT 10 v=spf1 mx a -all

https://tools.ietf.org/html/rfc6186

_submission._tcp     SRV 0 1 587 smtp.example.com.
_imap._tcp    SRV 0 1 143 imap.example.com.

RFC-2606 reserves 4 different TLDs for testing and documentation examples:

• .test
• .example
• .invalid
• .localhost

DO NOT use .local for testing or local purposes! It's reserved for mDNS – if you hand out .local DNS entries, you'll interfere with Avahi/Zeroconf hostname resolution.

try one of the following:

systemd-resolve --flush-caches
systemctl restart nscd
systemctl restart dnsmasq
systemctl restart named