# Failed to Add a Domain in IPAM - Domain Controller Not Reachable

## Problem

You are trying to add an Active Directory Domain in the IP Address Manager and you get an error as "Domain Controller is not reachable".

## Cause

When you add a domain in OpUtils, it fetches the details of the computer objects in the Active Directory from the Domain Controller. When it is not able to connect to the Domain Controller, you will get this error. This could happen in the following cases:

1. When the Domain Controller refuses remote connection
2. When you specify the DNS name of the Domain Controller and the IP returned from the DNS Server is not that of the Domain Controller
3. Network problem or when the domain controller is down

## Resolution

### Enable Remote Administration in the Domain Controller

For OpUtils to connect to the Domain Controller remotely you need to enable Remote Administration in the Domain Controller. Follow the steps below in the Domain Controller:

1. Click **Start** → **Run**
2. Type `gpedit.msc` and click **OK**
3. Expand **Computer Configuration** → **Administrative Templates** → **Network** → **Network Connections** → **Windows Firewall** → **Domain Profile**
4. Right-click **Windows Firewall: Allow remote administration exception**, and then click **Properties**
5. Click **Enabled**, and then click **OK**

### Correct DNS Errors

Check whether the DNS Server has been updated with the correct IP Address of the Domain Controller. Update the DNS record to correct the IP Address of the Domain Controller. Alternatively, try specifying the IP Address of the Domain Controller when you add the domain.

### Check if the Domain Controller is up and running

Check whether the Domain Controller is up and running when you add the domain in OpUtils. If it is running, check whether you are able to ping the Domain Controller from the computer where OpUtils is installed. If not, check the traceroute or other network problems and correct them before you add the domain.

**Applies to:** IP Address Manager  

**Keywords:** Active Directory, Windows AD, Domain Controller, Remote Administration Exception

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