Duplicate name exists in the network

[raaman rai]

My office server raises and error "Duplicate name exists in the network" on startup. I have tried finding the solution in the net but was of no use. Infact i understand that the problem has arised due to the same NetBios (Computer Name). The background information is that our office LAN is very small consisting around 8 to 9 computers. We have a server and the server is with two NICs, one for our LAN and other for the internet. Now the fact is that none of the PCs in my LAN have the same computer name as the server. Only the possibility is that my server name is conflicting with the ISP providers server name. So it means that my server is in a public domain which i am not secured of. Please how can i solve this problem?

[sicarie]

Take that server off the network, open up a command prompt and

ping <hostname>

In many cases, that comes back with the IP. If not, try a traceroute (tracert in Windows)

[Arulmurugan]

Hi,
If you think the name confilict with ISP name, remove the link which is conneced to public network and restart your server. If your server starts fine then the problem is public name problem, you have to talk with your ISP to solve this problem, otherwise problem is with your private network. use 'ping' to find out who is responding and solve it.
Regards,
Arul

[raaman rai]

Yes, if i disable the connectivity to my ISP provider, the system starts normally. Now i am bit against the second suggestion given by you because there are many private networks whose server name is the same as the ISP provider's server name. Still than they donot have this type of problem because they perform NAT. That is what i have done but still i have the problem. So i feel something is missing when i perform the NATing. If you could help me in this i would be grateful.

[Arulmurugan]

Yes, if i disable the connectivity to my ISP provider, the system starts normally. Now i am bit against the second suggestion given by you because there are many private networks whose server name is the same as the ISP provider's server name. Still than they donot have this type of problem because they perform NAT. That is what i have done but still i have the problem. So i feel something is missing when i perform the NATing. If you could help me in this i would be grateful.

My first question is, is it a new network? or it was working, but not now?

Generally NAT name should be public name given by ISP, not your own name.

You said problem is due to 'NetBios' which means, did you configured you NAT on Widnows BOX?.

I don't the same problem will faced by other people who are using NAT.
Generally the following is the way to assign the name.
assume you got 'xxx.com'( public name) 20.56.78.26 ( IP address) from ISP, it should be your NAT box name IP address.
your private network name as to be as follows.

host1.xxx.com 192.168.55.77
host2.xxx.com 192.168.55.78
host3.xxx.com 192.168.55.79

If you assign the name as above, will it give any problem with name?. i don't think so. still you are geting the problem. i think it is someting to do with ISP.
report this problem to ISP, before that do some kind of troubleshooting about this.

Regards,
Arul

[raaman rai]

ok to give you a clear picture, one of my NIC is given the private address of 192.168.0.1 and the other a public IP assigned by the ISP. My server has the computer name as SERVER. And i have configured the server computer to act as a NAT Server using the Routing and Remote Access. Now what i feel is that since my server computer name is SEVER, it is verymuch possible that my ISP also has its server name the same as above. So i think this is what is creating the problem. But on the other hand i feel if i have configured NAT, this problem should not exist. My network should be a private network and the NAT server should be able to differenetiate this one. Infact i am very confused and dont understand what the actual problem is.

[Arulmurugan]

ok to give you a clear picture, one of my NIC is given the private address of 192.168.0.1 and the other a public IP assigned by the ISP. My server has the computer name as SERVER. And i have configured the server computer to act as a NAT Server using the Routing and Remote Access. Now what i feel is that since my server computer name is SEVER, it is verymuch possible that my ISP also has its server name the same as above. So i think this is what is creating the problem. But on the other hand i feel if i have configured NAT, this problem should not exist. My network should be a private network and the NAT server should be able to differenetiate this one. Infact i am very confused and dont understand what the actual problem is.

Hi,

You are right!.., it is very much possible that the same name can be in ISP's domain. When you connect a machine into a public network you suppose not to give the name you like, it should be assigned by ISP.

Upto my knowledge for name conflicting, the machine will not start only in Windows, but other OS even with name conflict and a unique IP address, you can start a server.

I don't think some kind of NAT configuration would help for your problem.., not sure.. may be it can solve also.., i never configured NAT,
You can debug this as follows.
1.Remove your computer name or rename to a unique name.
2.Restart your server.
3.ping 'SEVER'( the name is your server's pervious name).
4.Now you can find out.., who is having this IP.

Note : Generally people will not assign a name to NAT server, because it may lead a security issue.

If you have more doubt on this you can chat with me at gtalk (umarul@gmail), India time 9 AM to 6 PM would be best time to talk.

Regards,
Arul