VTP client spontaneously becoming server?

Hello all,
I recently heard of an instance in which a VTP client was connected to a network without first being erased or having it's VTP revision reset to 0. The revision number on this client was higher than that of the network it was connected to and, according to the person I was speaking with, the vtp client promoted itself to vtp server and wiped out their vlan config.
My question is: Can this actually happen or has someone fed him a line? I've never heard of that occuring and cannot find any documents referencing anything like that.
Thanks,
--jesse

This does indeed happen. It's not that the client has become a server, it's just the normal behavior of a client is not what you might expect from its name. The VTP domain can be updated by clients as well as by servers; all that is needed is a higher configuration revision. The only difference between a server and a client is that the CLI in a client will not allow you to modify the database.
Kevin Dorrell
Luxembourg

Similar Messages

Fail to ping from VTP server to a host connected to VTP Client

Hi guys,
I have 2 3560 configured as VTP server and client, did all the trunk setup. A VLAN 102 172.100.4.254/24 created on server side.
Now I can ping the 172.100.4.211 and 172.100.4.254 from vtp client switch
but can't ping 172.100.4.211 from vtp server switch.
routing is handled by a 2811 which can also ping 172.100.4.211 and 172.100.4.254.
Any help is appreciated...

it's like this:
2811 - 3560(vtp server ) - 3560(vtp client) - ESXi
ip route VLAN 102 VLAN 102
172.100.4.254 172.100.4.211
VLAN 101 VLAN 101
172.16.70.254 172.16.70.201
And I just figured out the issue, the address 4.211 belongs to network node in a openstack, should be bind to a bridge instead of interface. thanks anyway!

Puzzling situation: XP clients cannot ping server while W7 clients can

We have an SBS 2011 server with XP and Win7 clients. The server provides DHCP and DNS services. Clients are all DHCP.
Another DHCP server was on the network, which caused the 2011 box to shut down DHCP services. We have fixed that and all is working now, but....
While troubleshooting, we found differences between the behavior of XP and W7 machines. All could still connect to the internet and ping the gateway. But only the W7 machines could communicate with the server (email, ping, DNS, RDP).
The XP machines could not even ping the server's IP address. Around 5-6 of each client OS were examined and the results were consistent. Examples of configurations are as follows:
Server
IP: 192.168.3.1
SM: 255.255.252.0
GW: 192.168.3.2
DNS: 192.168.3.1, 8..8.8.8
W7 client
IP: 192.168.0.20
SM: 255.255.252.0
GW: 192.168.3.2
DNS: 192.168.3.1, 8.8.8.8
DHCP: 192.168.3.1
XP client
IP: 192.168.1.26
SM: 255.255.252.0
GW: 192.168.3.2
DNS: 192.168.3.1, 8.8.8.8
DHCP: 192.168.3.1
Also, upon booting an XP machine, it would not get any IP address. After booting a W7 box, it would have the appropriate IP configuration and we were able to RDP to the server and browse the internet.
As I said, everything is working now after removing the foreign DHCP server, but we found the behavior odd and would like to understand why there were differences between the two client platforms.

Well, I can't really do this now, because everything is working. I know - why waste time trying to fix something that isn't broken. It just doesn't make sense to me.
I am just trying to determine why XP machines behaved in one way and W7 machines in another - but only while the DHCP service was down on the SBS box. I looked at several of each, so I don't think I was a problem with the IP stack, unless
all XP clients had the same issue at the same time, and all spontaneously resolved when the DHCP server came back up.
I tested multiple XP machines and multiple W7 machines in multiple buildings, so I'm confident that the problem was platform-specific.

VTP CLIENT ERASE VLAN INFO

Could you pls explain how can a new switch added as vtp client (with higher rev no.)erase vlan info.In some materials it says it can erase it,but some says it cant.Pls clarify

Incorrect.
SW-11 will ignore the VTP updates from other switches because of their lower configuration revision number. At the same time, other switches will receive VTP updates from SW-11 ,finding that the received updates has a higher revison number and thus replace their own vlan info with the received updates. At that time, all switches will have identical vlan information as SW-11.
A typical wrong concept is that switches in VTP client mode cannot overcome switch in server mode. There is no such a definition about VTP client mode. The true definition of VTP client mode , according to "Cisco Lan Switch" by Kenndy Clark, page 545, is that switch in client mode CAN source and listen to VTP messages, but CANNOT create and remember VLAN. ("source" means send out VTP message, "remember" means store VLAN info on the NVRAM)
According to this definition, switches in server mode and client mode will both send out VTP messages, and there is no rule that messages from server mode should beat the one from client mode. The rule is the revision number determines who will win. However, it is rarely possible to make switch in client mode to have an higher revision number than one in server mode. I have designed a lab to make this happen, described as follows.
I have 3 swithces and have them connect as below:
SW1---SW3---SW2
SW1 and SW2 are VTP servers, while SW3 is a VTP client. The connections among them are trunks.
First I create 10 VLANs on SW1. All switches have 10 VLANs and VTP revision number 10.
Then I shutdown the connection between SW3 and SW2. SW2 is isolated from others, but VLAN info among them is still the same
Then I delete 5 VLAN on SW1. Now SW1 and SW3 have only 5 VLANs and VTP revision number 15. SW2 has 10 VLANs and VTP revision number 10.
Then I shutdown the connection between SW1 and SW3. Now we have 3 isolated switches. SW3 have 5 VLANs and VTP revision number 15. SW2 has 10 VLANs and VTP revision number 10.
Notice that SW3 is in VTP client mode and have an higher revision number than SW2 which is a VTP server. Now I restore the connection between SW3 and SW2 so they can start to exchange VTP message, and the result is -- Client prevails Server. HOORAY!
Option A commit a wrong concept and hope someone fall into the trap. Unfortunately , this happens all the time.
HTH
SSLIN

Why my VTP client switch changes automatically to vtp transparent?

hi ppl!
i got a severe problem in my network. currently, we are implementing cisco 5509 catos based layer switch as our vtp mode server. so when i tried to hook up a new cisco 2950 switch by configuring it as vtp client with the same vtp domain name with dat of cisco 5509 vtp server mode, it will automatically change to vtp transparent mode but with the same vtp domain name. so, is there anyone dat can give me the best solution to mitigate my problem. e-mail me via [email protected]
dawit [B.Sc,CCNA,CCNP], Ethiopia
thanx

here is the configuration as per your request
version 12.1
service nagle
no service pad
service timestamps debug uptime
service timestamps log uptime
service password-encryption
service linenumber
hostname ccr6switch1
logging monitor notifications
aaa new-model
aaa authentication login default local
ip subnet-zero
no ip source-route
no ip gratuitous-arps
ip domain-name netdev.aau.edu.et
ip name-server 10.6.10.22
ip name-server 10.5.10.22
ip name-server 10.4.10.22
ip dhcp-server 10.6.10.100
vtp domain aau
vtp mode transparent
vlan 6
name 4kthin
said 10006
vlan 7
name 5kthin
said 10007
vlan 8
name thinclient
said 10008
vlan 9
name Multi
said 10009
vlan 10
name SSserverFarm
vlan 13
name ccr6_1
vlan 14
name ccr6_2
vlan 15
name ccr6_3
vlan 16
name ies1
vlan 17
name ies2
vlan 18
name sisa6switch1
vlan 19
name bued6switch1
vlan 20
name ken6switch1
vlan 21
name ken6switch2
vlan 22
name law6switch1
vlan 23
name reg6switch1
vlan 24
name ier6switch1
vlan 25
name glib6switch1
vlan 26
name idrl6switch1
spanning-tree extend system-id
no spanning-tree vlan 6
no spanning-tree vlan 7
no
no spanning-tree vlan 19
interface FastEthernet0/1
description from ccr6switch2
switchport trunk allowed vlan 1,11-15,300,301,1001-1005
switchport mode trunk
no ip address
interface Vlan1
ip address 10.1.0.6 255.255.255.0
no ip redirects
no ip redirects
no ip proxy-arp
no ip route-cache
ip default-gateway 10.1.0.2
ip http server
^C
AND THE SOFTWARE VERSION IS
IOS (tm) C2950 Software (C2950-I6Q4L2-M), Version 12.1(9)EA1, RELEASE SOFTWARE (
fc1)

VTP Client or transparent

We have a big facility that we are deploying about 25 2960's used for access switches. We have heard transparent is the best practice. Is this still true and if it is can someone tell me why? Throughout our environment, we have a cross of some running transparent and some running client. It would be nice to stick to some standard. Thanks!

VTP is a protocol that should be used carefully because it can lead to nasty effects. In regards to your question, there are some benefits when using transparent mode:
You can create private VLANs (they are not advertised through the trunk links).
You can create VLAN IDs from 1006 to 4094, 1024 limit is not a problem (extended VLANs are not saved in the VLAN database and are not propagated in this mode).
VTP and VLAN configuration are also saved in the switch running configuration file.
When you delete a VLAN from a switch that is in VTP transparent mode, the VLAN is deleted only on that specific switch.
In general, according to your network topology and your needs, the use of VTP is optional. If this switches are access switches, you can configure VTP Client in those you need the same VLANs. For example, if you have 10 switches that must be configured with the same VLAN info, that switches can be VTP Client and the others can be VTP Transparent (in order to forward VLAN info through all switches), but as I told you, this depends on what you need.
I suggest you to configure VTP Transparent in the switches you need to manually create VLANs and do not want to advertise them or configure private VLANs. Besides, for best practices and for security reasons, it is important to avoid sharing all VLAN info between all the switches. So, the switches that have VLANs with servers or do not have end user's VLANs, would be configured as VLAN transparent.
Configure VTP Client in the switches that will have the same VLAN info, then just configure a VTP server with the VLAN info and that is all, well, do not forget to do the proper configuration to share info between the switches (VTP domain, authentication, version, etc).
This link is useful to understand VTP:
http://www.cisco.com/c/en/us/support/docs/lan-switching/vtp/10558-21.html
This link is useful if you need help when configuring VTP:
http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3560/software/release/12-2_52_se/configuration/guide/3560scg/swvtp.html
Best Refards,

Newly created vLAN in VTP Domain issue with VTP Client

Hello,
I have a VTP Domain with WS-c4506 switch "server" and multiple c2950 "clients" along Microsoft DHCP server.
I have this infrastructure 5 years ago up & running without any problems but nowadays we need to add a new vLAN wireless access points i already created the vlan on the server checked it is created on clients show vlan found the new vlan.
I
assigned fa port to it on the core switch "server" i have the access point connected to it have some problems obtaining IP Address but it got fixed by restarting the DHCP server.
problem with VTP clients that when i try to assign port to the new vlan it always takes APIPA and even when i give the laptop connected directly to the port static IP address with the same range of the new vlan at acts like there is now networks exist it cannot ping anything within the network.
it all looks right but i dont know why it doesnt connect to the network like it should.
any recommendations?

Yes. I can Telnet over the site to site tunnel to the Cisco 881. I can not Telnet via the VPN Client to the Cisco 881 or ping it's LAN interface.
GM

In a vtp domain how many server mode switches can be

dear sir,
in a vtp domain how many server mode switches should be.
what role transpranent mode vtp domain and were we are using it.

Hi Mukhtar,
You can have all the switches in server mode in your network but it is always recommended to have atleast 1 and better to have 2 in your network.
One is required because VTP server is the only switch from where you can modify, add or delete vlan and it will be propogated to all client switch but 2 is recommended to have redundancy incase your one VTP server goes down you will be having another ot take care of your network.
Talking about VTP mode transparent, this mode will allow you to create,delete and modify any vlans but will not participate in any VTP messages and it will also not propogate its VLAN information to anyone in the network.
Also if you want to go for extended range of vlan which is above 1005 you have to configure your siwtch in VTP transparent mode only.
To know more about VTP have a look at this link
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat2950/12120ea2/2950scg/swvtp.htm
HTH, if yes please rate the post.
Ankur

Switch behaviour in VTP CLIENT mode

Hi all together!
In any configuration guide about Cisco switches in chapter about VTP mode following phrase presents "In VTP client mode, VLAN configurations are not saved in NVRAM."
What does it mean?
I've made some lab exersises and saw what after receive VTP update message, switch in CLIENT mode, write received information in vlan.dat file. And after reboot, when switch doesn't have trunk connections to any other switch, it has all vlan information but not vlan 1,1002-1005 only.
From that I make conclusion, what switch in CLIENT mode nevertheless stores VLAN informations in NVRAM (scope in the FLASH for conf. data)

Hi ankurbhasin!
I also used to think what it works in way you wrote above. But I say one more time:
I took 2950T-24 switch. Deleted vlan.dat file. Rebooted switch. Turn switch in CLIENT mode. Connected switch to another switch in Server mode with TEST domain name through trunk port. First switch received VTP update information, including VTP domain name TEST and some number of VLANs. After that I disconnect trunk cable and reloaded my 2950. How I writed in first post switch in client mode after reboot and no trunk connections to any VTP server or client had ALL informations about VTP and VLAN as before reboot.
And I ask you again what kind of information switch in clinet mode doesn't save into NVRAM?

Async tcp client and server. How can I determine that the client or the server is no longer available?

Hello. I would like to write async tcp client and server. I wrote this code but a have a problem, when I call the disconnect method on client or stop method on server. I can't identify that the client or the server is no longer connected.
I thought I will get an exception if the client or the server is not available but this is not happening.
private async void Process()
try
while (true)
var data = await this.Receive();
this.NewMessage.SafeInvoke(Encoding.ASCII.GetString(data));
catch (Exception exception)
How can I determine that the client or the server is no longer available?
Server
public class Server
private readonly Dictionary<IPEndPoint, TcpClient> clients = new Dictionary<IPEndPoint, TcpClient>();
private readonly List<CancellationTokenSource> cancellationTokens = new List<CancellationTokenSource>();
private TcpListener tcpListener;
private bool isStarted;
public event Action<string> NewMessage;
public async Task Start(int port)
this.tcpListener = TcpListener.Create(port);
this.tcpListener.Start();
this.isStarted = true;
while (this.isStarted)
var tcpClient = await this.tcpListener.AcceptTcpClientAsync();
var cts = new CancellationTokenSource();
this.cancellationTokens.Add(cts);
await Task.Factory.StartNew(() => this.Process(cts.Token, tcpClient), cts.Token, TaskCreationOptions.LongRunning, TaskScheduler.Default);
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foreach (var cancellationTokenSource in this.cancellationTokens)
cancellationTokenSource.Cancel();
foreach (var tcpClient in this.clients.Values)
tcpClient.GetStream().Close();
tcpClient.Close();
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await this.Send(tcpClient.GetStream(), Encoding.ASCII.GetBytes(message));
catch (Exception exception)
private async Task Process(CancellationToken cancellationToken, TcpClient tcpClient)
try
var stream = tcpClient.GetStream();
this.clients.Add((IPEndPoint)tcpClient.Client.RemoteEndPoint, tcpClient);
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var data = await this.Receive(stream);
this.NewMessage.SafeInvoke(Encoding.ASCII.GetString(data));
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private async Task Send(NetworkStream stream, byte[] buf)
await stream.WriteAsync(BitConverter.GetBytes(buf.Length), 0, 4);
await stream.WriteAsync(buf, 0, buf.Length);
private async Task<byte[]> Receive(NetworkStream stream)
var lengthBytes = new byte[4];
await stream.ReadAsync(lengthBytes, 0, 4);
var length = BitConverter.ToInt32(lengthBytes, 0);
var buf = new byte[length];
await stream.ReadAsync(buf, 0, buf.Length);
return buf;
Client
public class Client
private TcpClient tcpClient;
private NetworkStream stream;
public event Action<string> NewMessage;
public async void Connect(string host, int port)
try
this.tcpClient = new TcpClient();
await this.tcpClient.ConnectAsync(host, port);
this.stream = this.tcpClient.GetStream();
this.Process();
catch (Exception exception)
public void Disconnect()
try
this.stream.Close();
this.tcpClient.Close();
catch (Exception exception)
public async void SendMessage(string message)
try
await this.Send(Encoding.ASCII.GetBytes(message));
catch (Exception exception)
private async void Process()
try
while (true)
var data = await this.Receive();
this.NewMessage.SafeInvoke(Encoding.ASCII.GetString(data));
catch (Exception exception)
private async Task Send(byte[] buf)
await this.stream.WriteAsync(BitConverter.GetBytes(buf.Length), 0, 4);
await this.stream.WriteAsync(buf, 0, buf.Length);
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var lengthBytes = new byte[4];
await this.stream.ReadAsync(lengthBytes, 0, 4);
var length = BitConverter.ToInt32(lengthBytes, 0);
var buf = new byte[length];
await this.stream.ReadAsync(buf, 0, buf.Length);
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Hi,
Have you debug these two applications? Does it go into the catch exception block when you close the client or the server?
According to my test, it will throw an exception when the client or the server is closed, just log the exception message in the catch block and then you'll get it:
private async void Process()
try
while (true)
var data = await this.Receive();
this.NewMessage.Invoke(Encoding.ASCII.GetString(data));
catch (Exception exception)
Console.WriteLine(exception.Message);
Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.
By the way, I don't know what the SafeInvoke method is, it may be an extension method, right? I used Invoke instead to test it.
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Copy file from client PC to server in a web deployed application

I have developed one application using Oracle forms 6i, which is deployed on the web server.
I run this application from a client PC in Internet Explorer using internet.
I want to copy one file from the client PC to the web server.
I have done following things
- Created a shared folder on the server and given full rights to every one on this folder
- I use 'net use' command in my program to connect to this shared folder
- I use copy command to copy file from local client pc to server. This copy command I am executing using host command of my programming (PL/SQL: eg. host('copy abc.txt \\server\share\') )
But this does not work.
When I do the same thing in command window, it works.
(ie. Start-Run cmd to open command window and then type the above copy command)
Can you please tell me, how to copy a file from client PC to the sever in Web deployed application?
Thanks

I downloaded D2KWUtil from the link suggested by you. It has very nice example demo form. But the documentation provided says following
Using D2KWUTIL in Web Deployed Applications
The use of this library is not supported with Web deployed applications.
In a web deployment scenario not all functions within D2KWUTIL will work. Any function that interacts with the User Interface (such as those in the WIN_API_DIALOG package) will fail.
Any interaction with the O/S by other functions will all be executed on the NT server and will act within, or return information pertinant to, the environment on that machine. For instance GET_COMPUTER_NAME will return the Server’s name, not the name of the computer that the Client browser is running on. Likewise COPY_FILE will copy files in the Forms Server not on the Client.
Functions such as those in WIN_API_BITOP will continue to work without change.
so this will not work in web deployed application.
Any other suggestion?
Thanks

How can i load file into database from client-side to server-side

i want to upload file from client-side to server-side, i use the following code to load blob into database.
if the file is in the server-side, it can work, but if it in the client-side, it said that the system cannot find the file. i think it only will search the file is in the server-side or not, it will not search the client-side.
how can i solve it without upload the file to the server first, then load it into database??
try
ResultSet rset = null;
PreparedStatement pstmt =
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pstmt.setInt (1, docId);
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// Open the destination blob:
pstmt.setInt (1, docId);
rset = pstmt.executeQuery (
"SELECT content FROM docs WHERE id = ? FOR UPDATE");
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if (rset.next()) {
dest_lob = ((OracleResultSet)rset).getBLOB (1);
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File binaryFile = new File (fileName);
FileInputStream istream = new FileInputStream (binaryFile);
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OutputStream ostream = dest_lob.getBinaryOutputStream();
// Create a tempory buffer
byte[] buffer = new byte[1024];
int length = 0;
// Use the read() method to read the file to the byte
// array buffer, then use the write() method to write it to
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pstmt.close();
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ostream.close();
//dest_lob.close();
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conn.commit();
conn.close();
} catch (SQLException e) {

Hi,
Without some more details of the configuration, its difficult to know
what's happening here. For example, what do you mean by client side
and server side, and where are you running the upload Java application?
If you always run the application on the database server system, but can't
open the file on a different machine, then it sounds like a file protection
problem that isn't really connected with the database at all. That is to
say, if the new FileInputStream (binaryFile) statement fails, then its not
really a database problem, but a file protection issue. On the other hand,
I can't explain what's happening if you run the program on the same machine
as the document file (client machine), but you can't write the data to the
server, assuming the JDBC connection string is set correctly to connect to
the appropriate database server.
If you can provide some more information, we'll try to help.
Simon
null

Is it possible to lock the keyboard of a client from a server using java

please explain wheterit is possible to lock the keyboard of a client from a server using java

You want to process code on one machine, and thereby lock the keyboard on another machine? No, that's not possible. It is extremely far from possible.
Of course, if the client is running software with security holes in it you might hack into it and crash the thing. This will lock up the keyboard pretty good. I hope that's not what you want ...
Or are you talking about a setup where you already have code running on the client, and some sort of communication between client and server? In that case what you need to know is whether it is possible to lock the keyboard at all. Once you have figured that out, it is trivial to add the communication code to have the server software tell the client software to lock the keyboard.
So what do you mean with "lock the keyboard"? It's pretty easy to remove/disable all keyboard related listeners in your own application. It's a lot harder (and AFAIK impossible with pure java) to disable alt-tabbing out of the application. And impossible, except from exploiting security holes, to lock the ctrl-alt-delete-combination on windows machine.

ORA-03113 while connect from 8i client to 7 Server

Hi,
I have a Oracle 7.3.3 Server running on a SCO OpenSever 5.0.5 and a Oracle 8i Client 8.1.6.0.0 on a RedHat Linux 6.2.
When I try to connect from the client to the server by issue command "sqlplus user@test", it responses me "Error while trying to retrieve text for error ORA-03113". But when I run "netasst" to test the connection, it says the connection was sucessful.
Can anyone help? Here are my configuration files:
Listener.ora on Server side:
LISTENER=
(ADDRESS LIST=
(ADDRESS =
(COMMUNITY=TCP.world)
(PROTOCOL=TCP)
(Host=10.128.64.52)
(Port=1526)
STARTUP_WAIT_TIME_LISTENER = 0
CONNECT_TIMEOUT_LISTENER = 10
TRACE_LEVEL_LISTENER = OFF
SID_LIST_LISTENER =
(SID_LIST=
(SID_DESC =
(SID_NAME = test)
(ORACLE_HOME = /usr/app/oracle/product/7.3.3
(PRESPAWN_MAX=10)
tnsnames.ora on client side:
TEST.888.COM
(DESCRIPTION =
(ADDRESS_LISTS =
(ADDRESS =
(PROTOCOL = TCP)
(HOST = 10.128.64.52)
(PORT = 1526)
(CONNECT_DATA =
(SID = test)
)

Hi,
I don't have a 64 bit instance, but maybe another test will be usefull, try to get a connection with sqlplus on the server but via sqlnet like "user/passwd@tnsentry" I think if that also is not possible it is not the 64 bit issue but more that the listener itself coundn't etsablish a db connection, be aware tnsping is only testing if the listener is running and do not check if the listener is able to connect to the db.
Hope this helps a little to find your real proble ;-), Olaf

Problem with program hanging randomly on certain commands from win 7 pro client to SB Server

Having a problem with program hanging randomly on certain commands from Win-7 Pro Client to SB Server Both 64-Bit
Five other slower XP-Pro 32 Bit systems though they are older and slower systems do not seem to hang as readily if at all.
It has been very frustrating as the Client-System, SB-Server and Program should work w/o any hitches, but this seems to work fine @ times and then hang randomly.
Would appreciate any and all suggestions in assisting.... JimBAgde-MSS

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USE: \\yourserver\shared\dental\file.mdb
DO NOT: S:\\shared\dental\file.mdb
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VTP client spontaneously becoming server?

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