dnsip fqdn
dnsip
resolves fqdn,
and prints the IP addresses of fqdn
on a single line.
If fqdn does not exist, dnsip prints a blank line.
You can list several fqdns;
dnsip prints each result on a separate line.
Normally dnsip exits 0. If dnsip encounters a temporary problem that prevents it from determining the list of IP addresses, it prints an error message and exits 111. The same comments apply to the other programs described here.
dnsipq udn
dnsipq feeds the name udn through
qualification.
It prints the fully qualified domain name and IP addresses
on a single line.
If the fully qualified domain name does not exist,
dnsipq prints no addresses.
You can list several udns;
dnsipq prints each result on a separate line.
dnsname a.b.c.d
dnsname
does a reverse lookup for the IP address
a.b.c.d.
It prints the first domain name for that address.
If no domain names are listed in DNS,
dnsname prints a blank line.
You can list several IP addresses;
dnsname prints each result on a separate line.
There is also a dnsfilter program that reads IP addresses from its input and performs many reverse lookups in parallel.
dnsmx fqdn
dnsmx prints the MX records of fqdn.
If there are no MX records,
dnsmx prints an artificial MX record,
simulating the behavior of MTAs.
dnstxt fqdn
dnstxt prints the TXT record of fqdn
on a single line.
If there is no TXT record,
dnstxt prints a blank line.