+description:
+ Haeredes is primarily useful for ISP network administrators.
+ Customers will occasionally decide to switch hosts without alerting
+ the current host; this can cause two problems:
+ .
+ * With NS records, the previous host (at the very least) keeps
+ hosting a DNS zone that does nothing. If that host uses their
+ authoritative nameserver as a caching lookup server as well, it
+ may return incorrect results to queries about the domain in
+ question.
+ .
+ * For MX records, the situation is slightly worse. Most mail servers
+ will immediately accept mail for which the server thinks it is the
+ ultimate destination. If a mail server is configured as the
+ destination for a domain, but it is not the MX for that domain,
+ then mail submitted to that server may possibly be lost. It is
+ therefore important to remove domains from the old mail host as
+ soon as the MX record is changed.
+ .
+ Haeredes can alert administrators when NS/MX records are changed. More
+ detail can be found in the man page.
+ .
+ /Examples/:
+ .
+ Make sure example.com has the expected name servers,
+ [ab].iana-servers.net:
+ .
+ @
+ $ haeredes a.iana-servers.net b.iana-servers.net <<< \"example.com\"
+ @
+ .
+ If you use --no-append-root and your nameservers are rooted, you
+ must remember to supply the trailing dot yourself. Otherwise, you'll
+ get false positives.
+ .
+ @
+ $ haeredes --no-append-root \
+   a.iana-servers.net b.iana-servers.net \
+   <<< \"example.com\"
+ Domain \"example.com\" delegates somewhere else: \"b.iana-servers.net.\" \"a.iana-servers.net.\"
+ @
+ .
+ Check orlitzky.com against the expected name servers, using
+ d.gtld-servers.net:
+ .
+ @
+ $ haeredes --server 199.7.91.13 dns1.viabit.com dns2.viabit.com \
+   <<< \"orlitzky.com\"
+ @
+ .
+ Check orlitzky.com against only one of the expected two nameservers:
+ .
+ @
+ $ haeredes dns1.viabit.com <<< \"orlitzky.com\"
+ Domain \"orlitzky.com.\" delegates somewhere else: \"dns2.viabit.com.\"
+ @
+ .
+ Check a nonexistent domain (we provide no delegates, since we
+ know .bar will not be delegated):
+ .
+ @
+ $ haeredes <<< \"foo.bar\"
+ Domain \"foo.bar.\" not delegated.
+ @