dnsname - does a reverse lookup for the IP address 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 (1) program that reads IP addresses from its input and performs many reverse lookups in parallel. Normally dnsname exits 0. If dnsname encounters a temporary problem that prevents it from determining the domain name, it prints an error message and exits 111. dnsip(1), dnsipq(1), dnsmx(1), dnstxt(1), dnsqr(1), dnsq(1), dnstrace(1) http://cr.yp.to/djbdns.html