~4 min read • Updated Mar 1, 2026
1. What Is Multi Server Setup?
The Multi Server Setup (MSS) feature allows multiple DirectAdmin servers to communicate with each other. In all examples, we refer to:
- Box A – the master server (where you are logged in)
- Box B – the remote slave server
All synchronization is “push based,” meaning data is pushed from A → B and stored on B.
The original purpose of MSS was DNS zone mirroring, but its functionality has expanded significantly over the years.
---2. DNS Zone Transfer & Domain Check
Zone Transfer
When a domain’s DNS zone is saved on box A, DirectAdmin automatically syncs it to box B. This ensures both servers maintain identical DNS records.
Domain Check
This prevents creating a domain on box A if it already exists on box B. For example, if domainB.com exists on B, DirectAdmin blocks creating it on A.
Two way DNS clustering
You can configure:
- A → B
- B → A
This allows both servers to act as ns1/ns2 and host users independently.
---3. Restoring Users in a Multi Server Environment
If restoring UserA on box B while its DNS zone exists on B, use this setting:
On restore, check for domain conflict in domainowners
This changes the conflict check from named.conf to domainowners, preventing MSS from blocking the restore.
If deleting a user on A but want DNS to remain on both A+B, enable Leave DNS.
---4. User Check – Prevent Duplicate Usernames
The User Check feature prevents creating a username on A if it already exists on B.
Why is this important?
If multiple DirectAdmin servers share a single remote MySQL/MariaDB server (box C), usernames act as database prefixes. Duplicate usernames across A and B would allow users to see each other’s databases.
Solution: Enable User Check in both directions:
- A → B
- B → A
5. E Mail Accounts Synchronization
This feature synchronizes the email account list stored in:
/etc/domain.com/passwd
from box A → box B.
Important notes:
- It does NOT create users.
- It does NOT create domains.
- Both the user and domain must already exist on both servers.
6. Show All Users – Cross Server User Visibility
When enabled, the Show All Users page on box A also displays users from box B.
A new column indicates which server each user belongs to. Clicking a remote user provides a link to the remote server’s account view page (login required).
---7. User Accounts Sync (Experimental)
This feature is in ALPHA and disabled by default. When enabled, creating a user/domain on A also creates it on B.
It only handles:
- User creation
- Domain creation
- User deletion
It does NOT sync any other data. Useful when combined with Email Sync to ensure the remote server has the required user/domain structure.
---8. Remote E Mail Account Sync
This feature uses the API to log in as the remote user and replicate email actions.
Supported actions:
- Create email accounts
- Modify email accounts
- Delete email accounts
- Suspend/unsuspend email accounts
Not supported:
- POP disk usage reporting
- Send count reporting
Optional control files:
cluster_email_allow.listcluster_email_deny.list
Rules:
- If neither file exists → all users/domains sync.
- If allow exists → only items in allow sync (deny ignored).
- If deny exists → items in deny do not sync.
9. Initial Email Sync
If box A has email accounts and box B does not, run:
echo "action=rewrite&value=email_passwd" >> /usr/local/directadmin/data/task.queue
10. Handling Failures & Retry Logic
DirectAdmin uses task.queue retry logic if:
remote_dns_retries > 0
Example task entry:
action=sync&type=cluster&value=email&username=fred&host=1.2.3.4&count=10&request=longrequest
Where:
- username – user who triggered the action
- host – the failed remote server
- count – retries remaining
- request – URL encoded original request
11. Requirements for Email Sync
- User must exist on both servers.
- Domain must exist on both servers.
- Remote server must run DirectAdmin 1.48.0+.
- Login Key must allow
CMD_API_POP. - “Login As” must be enabled on the remote server.
Written & researched by Dr. Shahin Siami