I didn't think that feature fit. Would people really use a general DNS client for this? I use nslookup.
$ dig +short -x 209.216.230.240
news.ycombinator.com.
$ dog PTR 240.230.216.209.in-addr.arpa.
PTR 240.230.216.209.in-addr.arpa. 23h59m44s "news.ycombinator.com."
And yes, I use dig -x quite often.As an example: I sometimes run 'curl ifconfig.me' to get my public IP from the command-line, but I wouldn't expect curl to add an '--ip' option to make this specific query easier to run. curl is a general tool, and the fact that you can use HTTP to get your public IP doesn't mean it needs a top-level option in an HTTP client. (I get that reverse lookup is an internet standard, and ifconfig.me is a third-party service, but still.)
dog 209.216.230.240
should directly perform a PTR lookup instead of requiring something like dog -x 209.216.230.240
Here's how host works when you give it an IP address as opposed to a domain name: $ host 209.216.230.240
240.230.216.209.in-addr.arpa domain name pointer news.ycombinator.com.
$ host news.ycombinator.com
news.ycombinator.com has address 209.216.230.240If it can see that an argument is an IP address and automatically do the PTR lookup for me, even better!