Local hostname involuntarily changed

[rg-easton]

Any idea what this system message means and how to stop this?

"This computer's local hostname, Mac Pro=4 local is already in use on this network. The name has been changed to Mac Pro-5". To change the local hostname, open System Preferences and click Sharing , then click edit and type the name in the local hostname field.

 

[MacsRgr8]

It means that another Mac on your LAN (local network) has the same "Sharing Name", and therefore the Mac that is booted later will get this message.
You cannot have two identical computer (sharing) names in a network.

It is wise to set everyone's Computer name as a unique name.
Most common is <Owner of Mac - Mac Type>, i.e. "Rg-easton Mac Pro".

You can do this in System Prefs >> Sharing, and then edit "Computer Name"

 

[Maedchen]

Hi, I only have one imac hooked onto my netscape wifi router, no other computer or mac attached to it. Now my imac tells me, I shall change the hostname from ....-1 to ....-2, since ...-1 is already in use. Has someone be accessing my router or is htis merely the Mac still believing it is connected to the router and I want to establish a second connection, i.e. it believes I am a second Mac wanting access?
Am a bit suspicious.
Any thoughts?

 

[Pinkerton]

I've had the same or a similar issue. My computer was constantly renaming itself with a (2) every time it booted, after a system lockup. I tracked the issue down to CD/DVD sharing... when turned off the problem went away.

When CD/DVD sharing was on, I could not change the name back to the original version, it would get rejected and immediately set back to the version with "(2)", displaying the message:

The name of your computer "Name" is already in use on this network. The name has been changed to "Name (2)" automatically.

With CD/DVD sharing turned off, I could name my computer whatever I liked, even back to the original name. Turning DVD/CD sharing back on again would instantly rename my Mac. It's very persistent bug!

Fortunately I found a fix. I was able to get rid of the problem by toggling Bonjour, as described here:

http://tech.karbassi.com/2007/11/06/leopard-turn-off-bonjour-mdnsresponder/

To turn Bonjour off:

sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist

To turn it back on:

sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist

Toggling Bonjour (mDNSResponder) forced a reset of something on my system somewhere, and now I no longer see the issue on reboot, even with CD/DVD sharing turned on. I can turn sharing on and off at will, and my computer is never renamed. Success!

I don't think this problem has to do with CD/DVD sharing specifically... I think it's a bug in Bonjour. I've seen threads where people have complained about this issue because of printer sharing, or remote management! My guess is that a crash can cause a mDNSResponder config corruption, tricking Bonjour to share devices or services using the same name as your computer, forcing the name conflict.

In any case, I hope this fix works for you too. I know I'm a lot happier now that there isn't a lingering issue on my box!