Configure Files for Sites in a Web Farm

If your Enterprise Portal site is not a part of a web farm, skip this procedure. Use
the following procedure to specify values for machineKey properties in the
web.config file of each server in the web farm. MachineKey properties
(validationKey and decryptionKey) are used for hashing and decrypting
authentication tickets and cookies. Values for machineKey properties must be the
same on all servers in the web farm. If they are not, Enterprise Portal pages might
display authentication and access errors.

1. On the web farm administration server, open the web.config file in a
text editor such as Notepad. By default, the file is located in the
following directory:

C:\Inetpub\wwwroot\wss\VirtualDirectories\PortNumber.

2. Locate the machineKey section and copy the validationKey and
decryptionKey values to a separate text file. The following is an
example of a machineKey section:

<machineKey
validationKey="4785A9C8F5FA32B47E5245AC48671291F1CE55
735A475EB7"
decryptionKey="D961976E181646326D64E01AB2052F5D076F0A
BDE2C702FB" validation="SHA1" />

3. Edit the web.config files on the other servers in the web farm.
Replace the existing machineKey values with the values that you
copied from the web farm administration server.
For more information about how to configure machineKey properties, refer to
How to: Configure MachineKey in ASP.Net 2.0

(http://go.microsoft.com/fwlink/?LinkId=117441), and specifically read the
section called "Web Farm Deployment Considerations."

Regards,
Hossein Karimi