In SharePoint environment people picker is one of the main
part in the farm to provide the users available from all the domains to select
the users. By configuring stsadm commands we can grab the users from different
domains.
SharePoint will use Application pool identity to search
users in active directory. If application pool account is not having permissions
to do that, we have to encrypt the password.
To do that we can use following command in STSADM,
stsadm -o setapppassword -password password
We have to set the domains should be searched on WFE for each
web application,
stsadm -o setproperty -pn peoplepicker-searchadforests –pv domain:domain1;domain:domain2,domain2\account,password -url WebApplication
Hope this helps.