You want to evenly distribute connection objects between bridgehead servers in a site.
To see what changes the command would make, run it without the /commit option. To actually make the changes in Active Directory, use the /commit option:
> adlb /server:<DomainControllerName> -site:<SiteName> [/commit] [/verbose]
Bridgeheads can become overloaded or end up with too many connection objects in relation to other bridgeheads in the domain. The Active Directory Load Balancing (ADLB) tool allows you to balance the load of connection objects among bridgehead servers within a site. The Windows Server 2003 algorithms are much better than Windows 2000 for load balancing connection objects across servers, but that process happens only when new connection objects are added. You can use the adlb tool to load balance the connection objects more efficiently at any time.
I recommend viewing the changes adlb would make first before using the /commit option. It is always good to do a sanity check to ensure adlb doesn't mess up your replication topology.