What is the difference between "ip domain name" and "ip domain-name"?

Question

I'm running a ISR 4221 with "Cisco IOS XE Software, Version 16.04.02".

I see that it has both ip domain name and ip domain-name commands. Why? Is this some sort of compatibility thing? My 7206 seems to prefer ip domain-name.

Just curious.
-Erik

Answer 1

They are the same.

Cisco IOS also supports the command ip domain name starting from its 12.2 Software release.

You can check it here:

• IOS: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr/command/ipaddr-cr-book/ipaddr-i3.html#wp1026378069

• IOS-XE: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr/command/ipaddr-xe-3se-3850-cr-book/ipaddr-xe-3se-3850-cr-book_chapter_01.html#wp1026378069

Answer 2

The two forms are equivalent. "domain-name" is the older form, and newer versions seem to prefer "domain name". Maybe at some point Cisco realized that removing the hyphen allowed them to extend the "ip domain ..." command line, i.e. you can have:

   ip domain name <xxx>
   ip domain <some other domain related function>
   ip domain <yet another domain related function>