Each windows domain controller has several SRV records that client use as part of the DC locator process to find the closest domain controller. Two fields of the SRV record let clients determine which server to use when multiple possibilities are returned. The Priority field is used to dictate if a specific server or set of servers should always be contacted over others unless otherwise unavailable. A server with a higher priority( Lower field value) will always be contacted before a server with a lower priority.
First let's check the existing priority and weight of the domain.
The weight value is stored in the LdapSrvWeight registry entry. The default value is 100, but it can range from 0 through 65535. By reducing this value, DNS refers clients to a domain controller less frequently based on the proportion of this value to the value of other domain controllers. For example, to configure the system so that the domain controller hosting the PDC emulator role receives requests only half as many times as the other domain controllers, configure the weight of the domain controller hosting the PDC emulator role to be 50. DNS determines the weight ratio for that domain controller to be 50/100 (50 for that domain controller and 100 for the other domain controllers). After you reduce this ratio to 1/2, DNS refers clients to the other domain controllers twice as often as it refers to the domain controller with the reduced weight setting. By reducing client referrals, the domain controller receives fewer client requests and has more resources for other tasks, such as performing the role of PDC emulator.
Adjusting the priority of the domain controller also reduces the number of client referrals. However, rather than reducing it proportionally to the other domain controllers, changing the priority causes DNS to stop referring all clients to this domain controller unless all domain controllers with a lower priority setting are unavailable.
A domain controller's priority value is stored in its registry. When the domain controller starts, the Net Logon service registers with the DNS server. The priority value is registered with the rest of its DNS information. When a client uses DNS to discover a domain controller, the priority for a given domain controller is returned to the client with the rest of the DNS information. The client uses the priority value to help determine to which domain controller to send requests.
The value is stored in the LdapSrvPriority registry entry. The default value is 0, but it can range from 0 through 65535.
Important: A lower value entered for LdapSrvPriority indicates a higher priority.
To change the weight for DNS SRV records in the registry:
1.Click Start, click Run, type regedit and then press ENTER.
2. navigate to HKLM\SYSTEM\CurrentControlSet\Services\Netlogon\Parameters
3. To configure the Priority, add a REG_DWORD with the name LdapSrvPriority.
to configure the Weight, add a REG_DWORD with the name LdapSrvWeight.
After you make the change, \System32\Config\netlogon.dns file should be updated and the DDNS updates sent to the DNS server within an hour. You can also restart the NetLogon service to expedite the process.