Hostname Already in Use Changes?

Frequentlly, we get "this computer's local host name on the network is changed to 1234567654-1 because it determines that the original host name "is already in use." This doesn't make network peripherals and communication between our two computers very easy. When we get the notice, we change the name (number) back to the original and it seems fine for awhile and then returns...
I can find no apparent cause?
Thanks!

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Local hostname already in use - can't figure out what's going on

I've been having issues with a wireless router and I think the problem lies somewhere within my computer. As I switch back and forth from trying to connect to the internet via my router or directly connected to my cable modem, I will often get this error:
"This computer's local hostname "xyz" is already in use on this network"
There is only one compuer on the network, however and I cannot figure out what's going on.
I have 2 users set up on this machine, but I'm the admin and acting as such. Even with no other networked equipment hooked up to my Mac (except for the cable modem) this problem won't go away.
I guess my real quesiton is what causes this and where should I go to troubleshoot things?
I'm running 10.4.6, connect to my ISP using DHCP and have the same problem with both a D-Link and Linksys router.
Any ideas?
Thanks!

Thanks very much for your help, fu.
If your previous setup follows a flow like this: RCA
CableModem-->NetGear Router-->AirPortExpress, there's
something misconfigured routing-wise in your network.
You have to decide which device (Netgear or AirPort
Xpress) will handle the routing in your network.
Previous to these problems, that was the basic flow of my network. The netgear router also fed a wired connection into a Wintel PC, and the AirPort Express hosted a wireless network that was extended by a second Airport Express. And that second AE connected to a ReplayTV with a wired connection. And then, of course, the PowerBook got Internet access wirelessly through the AE-hosted network. And that was it.
That network always was configured so that the netgear router assigned IP addresses using DHCP, and the Airport Expresses would not assign IP addresses (i.e., "Distribute IP addresses" was NOT checked when you look at the configuration in Airport Admin Utility).
How big is your network j? just 1 Mac (your
PowerBook)?
That was the state of the network a couple of days ago when I posted this. I have established that the PowerBook gets access to the Internet just fine directly though the cable modem, and just fine when it is the only wired connection to the router.
Let's deal with your Mac first:
Start with your Mac connected directly to the cable
Modem. (When your mac is attached directly to the
Cable Modem, do you use DHCP?)
Go to SystemPreferences-->Sharing and type a Computer
Name other than the default one
Open Applications-->Utilities-->Terminal and type
lookupd -flushcache (press Return) and reboot
the Mac.
I did this.
One way to fix your network is to have the NetGear do
the routing, and the AirPort Express to (just) extend
your (wired) network wirelessly (No routing will be
done from the AirPortXPress, (No distribution of IP
Addresses)
I soft reset both of my Airport Expresses. I configured the first one so that it was hosting a network, but not distributing IP addresses, and the second so that it was extending that wireless network. And I plugged the host AE into the netgear router. And for a little while, that was working.
But then I got a message saying "IP Configuration 192.168.0.4 in use by 00:04:40:06:1f:82, DHCP Server 192.168.0.1". The dialog box with that message will come up periodically as long as the Airport Expresses are plugged into power and one is plugged into the router. Also, I once agaiin received the message saying the local hostname (the completely original one that I had created) was in use, and the name was being changed.
Here is the thing. I cannot figure out what has that ...0.4 IP address and ...1f:82 MAC address on the network. That is not the "Internet port MAC address" or the "LAN port MAC address" for the Netgear router. It is also not the MAC address for either of the Airport Expresses or the PowerBook's internal Ethernet card.
I accessed the router through my browser, and clicked on "Attached Devices." Here is the list of Attached Devices:
# IP Address Device Name MAC Address
1 192.168.0.2 00:11:24:08:4c:88
2 192.168.0.3 00:14:51:6d:15:7c
3 192.168.0.5 00:0a:95:da:4f:24
The first two addresses are the two AE's, and the third is the internal Ethernet card of the PowerBook.
I ran "Netstat" under the Network Utility to get "Routing Table Information," and here is what I get (with some identifying info removed):
Internet:
Destination Gateway Flags Refs Use Netif Expire
default 192.168.0.1 UGSc 23 10 en0
127 localhost UCS 0 0 lo0
localhost localhost UH 11 2400 lo0
169.254 link#4 UCS 0 0 en0
192.168.0 link#4 UCS 3 0 en0
192.168.0.4 link#4 UHLW 1 1 en0
192.168.0.5 localhost UHS 0 14 lo0
Internet6:
Destination Gateway Flags Netif Expire
localhost link#1 UHL lo0
localhost Uc lo0
localhost link#1 UHL lo0
link#4 UC en0
justin-and-***** 0:a:95:da:4f:24 UHL lo0
**************bedro 0:14:51:6d:15:7c UHLW en0
link#5 UC en1
justin-and-***** 0:a:95:f3:3e:df UHL lo0
**************bedro 0:14:51:6d:15:7c UHLW en1
ff01:: localhost U lo0
ff02::%lo0 localhost UC lo0
ff02::%en0 link#4 UC en0
ff02::%en1 link#5 UC en1
Any ideas? Thanks again for your help.

Local-hostname-already-in-use message regularly appearing

I have seen some earlier posts here about this problem but no one seems to have resolved it.
Often when I wake my iMac (Intel, 10.5.4) from overnight sleep there is a message greeting me "This computer's local hostname 'XX.local' is already in use on this network. The name has been changed to 'XX-2.local'." I got as far as XX-65 the other day and thought it might be time to seek a solution.
There is a router, a laptop, and a couple of Slim Devices/Logitech Squeezeboxes on the network. None has the same name as the iMac.
It's driving me bonkers. No harm done, of course, but it's a real pain to keep changing it back to the original name, and still it keeps bombarding me with these messages.
Any thoughts, oh wise ones?

It is possible that your router is also acting a local dns server and as such caching your devices host names.
A fix for this would be to assign a fixed ip address to your mac.

Sudden message re "hostname already in use"

This morning when I opened my computer, a message was displayed saying: "This computer's local hostname "xxxx" is already in use on this network. The name has been changed to "xxxx"." I had done nothing to change the hostname. What could have caused the message to appear? Is this a sign that someone has hacked into my network somehow?

This usually means another computer on your network is using the same hostname. However, users with only one computer also report this error on occasion. It's not clear what exactly causes it to happen, but you can change it back to what you were using in the Sharing preferences pane.
You will find an interesting discussion and possibly permanent solution here: Prevent the Terminal host name from changing.

Does anyone have a fix for the "Local Hostname Already in use..."-bug?

I get this message + an incremental change in hoist name upon each wakeup (iMac, not me!) from sleep. I need a permanent fix, I would not like to play with Aiport settings etc. This issue came afetr upgrade to OSX 10.7.4. Will Mountain Lion fix it?
Mike

Tuomasveturi wrote:
I get this message + an incremental change in hoist name upon each wakeup (iMac, not me!) from sleep. I need a permanent fix, I would not like to play with Aiport settings etc. This issue came afetr upgrade to OSX 10.7.4. Will Mountain Lion fix it?
Mike
Never seen it. What makes you think it is a bug? Have seen no reports of it. Sounds like it is all within your settings.
Pete

Every time i wake my mac i get This computer's local hostname "D-360.local" is already in use on this network. The name has been changed to "D-444.local".

error message that my local host name is in use and the system generates a new one every time I wake my mac the error mssg reads This computer’s local hostname “D-360.local” is already in use on this network. The name has been changed to “D-444.local”.

There are several possible causes for this behavior.
1. Two (or more) computers on the local network have the same Bonjour name, such as "X's-MacBook-Pro.local". Resolve the name conflict by renaming one or more of them in the Sharing preference pane.
2. You have two simultaneous connections to the same local network: probably Ethernet and Wi-Fi. If applicable, disconnect the Ethernet cable or turn off Wi-Fi.
3. A Mac wakes from sleep due to network traffic. This is a bug in OS X that may only affect some models.
4. A device that gets its network address from the router wakes from sleep, and the address it was using before has been assigned to another device.
5. A third-party wireless router has incompatible settings or firmware. In that case, refer to the manufacturer or ISP for support. Restarting the router may help, temporarily.
6. See also this support article.

What does this mean? This computer's local hostname "Linda-Daviss-iMac-4.local" is already in use on this network. The name has been changed to "Linda-Daviss-iMac-5.local".

What does this mean: This computer’s local hostname “Linda-Daviss-iMac-4.local” is already in use on this network. The name has been changed to “Linda-Daviss-iMac-5.local”.
When I came back to my computer this message was on the screen. Should I be concerned ? or doing something?

Sometimes this message means that you have two simultaneous connections to the same local network: probably Ethernet and Wi-Fi. Disconnect the Ethernet cable or turn off Wi-Fi.
Sometimes it happens because a device that gets its network address from the router wakes from sleep, and the address it was using before has been assigned to another device.
Rename the computer in the Sharing preference pane.

Should I ok "this computer's local hostname Irma-Mac-mini-local" is already in use on this network. The name has been changed to Irma2 Mac-mini 2-local

Should I ok this message-this computer's local hostname Irma's Mac-mini-local is already in use on this network. The name has been changed to Irma's Mac-mini-2local

Don't think this is a conflict with IP Addresses or computer names
= DHCP hangover when computer renews DHCP lease
There is no actual other computer
It just appears that way when reconnects so creates new -2 computer name
What types of names do you use your computers ?
Whether you name them after quantum particles or the romantic poets...
They will each start to be appended with "-2" then "-3" etc if you auto configure network settings from Airport Router DHCP service and you have this Change computer name issue where pop up window states name is already being used on your LAN
As stated previous post you can reset the computer name in SysPrefs / Sharing / Edit button
And restart Router or renew all DHCP leases (if persists in not allowing original name)
Can now press Edit and reset name of choice
But for Fix see link above

I get this message:This computer's local hostname "x-8.local" is already in use on this network. The name has been changed to "x-9.local" I have turned off sharing and it continues to upgrade name. What is the fix?

I get this message: This computer’s local hostname “x-8.local” is already in use on this network. The name has been changed to “x-9.local” I have turned off sharing and it continues to upgrade name. What is the fix?

Hi, this is a common problem, mostly just irksome though.
It can have many cause, like using more than one Interface for connections, Router temporarily losing x.local & seeing a new connection with x.local already used, insists it must be x-1.local, x-2.local, etc..
What all Sharing do you have enabled?
Some possible fixes...
http://forums.macrumors.com/showthread.php?t=542899
https://discussions.apple.com/thread/3941367

HT5167 Error after 10.7.4 upgrade..."computer's local hostname ........is already in use on this network. The name has been changed to...... What to do now to get it back to status before 10.7.4 upgrade?

Error after 10.7.4 Lion Upgrade to iMac
Computer's local host name .......is already in use on this network. the name has been changed to........
and it keeps adding up the number each time I wake the iMac.
What to do to get it back before upgrade error?

Ok worth repeating, hope this works. Finally spoke to AppleCare Support and walked me thru following...restart computer holding down "command" and "option" keys at the same time with letters "P" and "R" when computer turns on. This is what he called a PR restart, clears out discrepancies in memory (if that is what the error message actually is). Then went to Systems Preferences/Network/Sharing and deleted the number that kept increasing every time MAC would wake up.
Even tho this was just done, I am hopeful that error pop-up won't happen again. Fingers crossed!

Why do I get the messagehis cowhy do I get the messageThis computer's local hostname "lenajs-imac.local" is alreamputer's local hostname "lenajs-imac.local" is already in use on this network. The name has been changed to "lenajs-imac-2.local".

why do I get the message "this computers local host name ______is already in use by the network

Usually this message means that you may have two simultaneous connections to the same local network: probably Ethernet and Wi-Fi. Disconnect the Ethernet cable or turn off Wi-Fi. If that's not the issue, shut down any virtual machines (Parallels, VMware, or VirtualBox) that are running. Rename the computer in the Sharing preference pane.

This computer's local hostname is already in use. How can I fix this?

Almost every day the following message appears in a pop up box.
This computer's local hostname "my-iMac-6.local" is already in use on this network. The name has been changed to "my-iMac-7.local"
The numbers do not correspond to those in the name in the Security preferences.
I preformed the "fix" described in the discussion.apple.com/messages---/messageID=9113111.
Set "iPv6" from "Automatically" to "Off" in both Airport and Ethernet.
That is apparently not the answer either.
There is only one computer in my house with the name shown in the message.
My wife's iMac has her name in it. Mine has my name in it.
How can I fix this?
Thanks for any help you can provide.
Rob Morrison

This seems to be a DHCP issue when the lease is renewed
When the computer reconnects (renews the lease) it believes its own computer name "already has been taken" so because the router has retained it on the local network so your computer inserts the after its computer name a
"-2" then a "-3" then "-4" etc. (the mac needs to do this and does so by default to ensure and create its own unique name on the local network)
-> this appears to be a delay / hangover on the router (AE or TC) when using DHCP
have seen a fix which only requires you set your computer with a fixed IP address
(can be EITHER reserved on the router OR set on the computer itself in network settings)
Router (AE or TC) Airport Utility 5.6 / Internet tab / DHCP button / click the "+" button & you reserve the computer's IP address by EITHER its MAC address (= shown in SysPrefs/Network/Advanced/Hardware) OR a DHCP client id (which you choose yourself) & enter exactly the same identical passphrase on the computer in sysprefs/network/advanced/DHCP(->set ro "using DHCP") shows textbox to enter the DHCP id
THEN apply with Update button (Router restarts)
Computer itself - under sysprefs / network -> Configure IPv4 to "Using DHCP with Manual Address" (will autofill from DHCP) check correct local IP address of computer is set & click Apply OR "Manual Address & manually enter the settings for local IP Address of computer / subnet mask / router's Ip address / DNS server's IP address / (DNS) Search Domain (optional)
Since setting static address this problem has not re-occurred.
Thanks to MacFixit there is a terminal fix here (from Sept 09) as well : http://reviews.cnet.com/8301-13727_7-10362633-263.html?part=rss&tag=feed&subj=Ma cFixIt

This computers local hostname is already in use?

I turned on my computer this afternoon and was met with this message:
"This computer's local hostname "Name of my hard drive.local" is already in use on this network. The name has been changed to "The name of my hard drive-2.local"
To change the local hostname, open System Preferences and click Sharing, then click "Edit" and type the name in the Local Hostname field."
Can anyone tell me why is this happening? I've never seen this before. Has my computer been compromised?
Thanks

Sorry--I missed that first time around. I think you would do better by reposting in the Forum for OS10.5. You have a software issue and that forum will have more software gurus. Machine-specific forums are better for hardware issues, but I think your hardwre is probably fine.
If you wish, I can ask the Hosts to move this for you so you need not do anything. Let me know.
OSX 10.5 forum is here:
Mac OS X v10.5 Leopard

This computer's local hostname is already in use on this network

has anyone else experienced this issue?
The iMac will display the following error message on the screen every day or so (with the host number incresing by 1 digit each time):
This computer's local hostname "MacName.local" is already in use on this network.The name has been changed to "MacName-1.local". This continues even after I've reset the name in the System Preferences panel/sharing settings, for example ("MacName-2.local, MacName-3.local, MacName-4.local" etc).
Please advise
Currently running an Apple iMac
OS 10.6.8
*please see attached screenshot for a reference

(1) Check names of all other devices on the network, including the router, any airport express, iphone, ipad, printers etc. Make sure these all have unique names.
(2) Do you have both wired ethernet as well as wireless active on any of these devices, including the Mac computer? This has been linked to such renaming behavior in the past, apparently the two methods of accessing the internet, if both are active at the same time, may switch off and on and conflict with one another (shouldn't happen, but apparently does sometimes). Solution is to switch one of them off.
(3) The following may be helpful:
In System Preferences > Network > Airport > Advanced > TCP/IP
Set "Configure iPv6" from "Automatically" to "Off".
If you do this, check to make sure that your email and other tools are still working properly. If something goes amiss, change the iPv6 back to what it was.
(4) Go to your router and reset power to it.
(5) Go to your router and check its LAN client table. Make sure that all entries should be there. Investigate any "extra" devices on the network. For instance, if it shows 4 devices, but you know you have only a computer and a printer, investigate what the other two are. Delete them from the list if they really seem to be "ghosts."

Local Hostname is already in use on this network

Hi,
Since upgrading to OS X 10.8 and then 10.8.1, I receive the following message when waking the iMac from sleep, "This computer's local hostname (see screen shot below) is already in use on this network". Earlier today, I went into the "Sharing" properties and changed the hostname to ShaneiMac and as you can see from the screen shot, it just renames it with a -2. It doesn't appear to be causing any issue in regards to performance of the machine but it's getting annoying. Is there any way to fix this?
Thanks.

Then this fix may work for you!
Warning, this may break your ability to use back to my mac.
Open Network preferences, select your network port (Airport or Ethernet) and click on the Advanced button. Click on the TCP/IP tab and set the Configure IPv6 drop down menu to Off. If you use both ports then make the same change for both ports.
Open Sharing preferences and reset your Computer Name.

Hostname Already in Use Changes?

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