When you need to demote a domain controller in an Active Directory domain, a few considerations will need to be taken into account to ensure the process runs smoothly. Here are some points to consider:

1. Identify the domain controller: Find the name of the server and the IP address.
   
2. Check local area network: Make sure your LAN is properly functioning, as the demotion process requires connectivity between the server and all others connected to the LAN.
   
3. Prepare for demote: Check the health of the domain controller. Ensure that replication is working and no replication errors have been reported. Make sure all users and services are logged off the computer.
   
4. Force replication: Run the command repadmin/syncall to ensure that all data from the domain controller in question has been replicated to other main controllers.
   
5. Backup Active Directory: Ensure that Active Directory database is backed up on a regular basis, if you haven't done it as yet.
   
6. Run Dcpromo command: Run the Dcpromo command to demote the domain controller and consider the domain options displayed.
   
7. Verify demotion: After the demotion process, ensure that all domain controllers have updated connection objects to track the links between the servers and the demoted server. Check the event log for any errors.
   
8. Backing up data: It is prudent to make a backup of all data stored in the server before it is decommissioned.