I was asked to change the IP address of the management interface on our firewalls but not issue "no ip address" because it will put the interface in shutdown mode which needs to issue no shut again and simply just apply the new ip address. I could not try this to see if it actually happens because it's production environment so here I am. Is that right if I issue no ip address on the management interface, it goes to shutdown mode?
No Ip Address command does not put the interface in a shutdown state. However, I believe your coworker is telling you that your telnet session will be dropped if you issue this command which is correct. Because you would no longer have a management address, you would also no longer have a session using the address set.
If you have to issue the
No Ip addresscommand, do so from a console connection to avoid losing your session.