The DNS zone edition page in your account allows you to configure and delegate sub-zones within your domain to other name servers than.
Such sub-delegation is configured with NS records:
2. Move the cursor over the concerned domain and click on Manage on the right.
3. Click on MANAGE ZONE.
4. Click on NEW RECORD.
5. Select NS (Name Server for sub-zone delegation) in the Type dropdown menu.
6. Enter the name of the sub-zone in the host part and the name server in the Name Server part (please don't forget to enter the "." at the end. For example: "ns1.example.com.")
7. Click on SAVE RECORD.
8. Repeat steps 4 through 6 for the other name servers for the same sub-zone.
9. Click on SAVE ZONE.
Note: DNS changes usually need up to 24 hours to propagate throughout the entire Internet.
Important: This option is only available if the domain is using name servers (default name servers: ns1 / ns2).