Windows Server DHCP Scopes and Failover Operations

Use this workflow to inspect Windows DHCP scopes, plan a small change, and verify a failover relationship. Examples use documentation-only subnets. A DHCP scope controls address leases and options for a subnet; changing it can disconnect clients or hand out incorrect gateway and DNS settings.

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01

Inventory the DHCP Server and IPv4 Scopes

Read First

Run the DHCP Server module from an elevated administrative session with the required network permissions. Confirm the server name and authorization before making changes. Remote commands can use -ComputerName.

Get-WindowsFeature DHCP
Get-DhcpServerInDC
Get-DhcpServerv4Scope -ComputerName 'dhcp01.lab.example' |
  Format-Table ScopeId, Name, State, StartRange, EndRange, SubnetMask

❯ View Expected Console Output

ScopeId       Name         State  StartRange    EndRange      SubnetMask
-------       ----         -----  ----------    --------      ----------
192.0.2.0     Lab-Clients  Active 192.0.2.50    192.0.2.200   255.255.255.0

DHCP MMC: Inspect active leases in the selected IPv4 scope.

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02

Review the Pool, Exclusions, Reservations, and Options

Scope Design

Check whether planned addresses overlap with static infrastructure. Inspect exclusions, reservations, lease duration, and options such as router (003), DNS servers (006), and DNS domain name (015). Confirm the option values with the network and DNS owners.

$server = 'dhcp01.lab.example'
$scope = '192.0.2.0'
Get-DhcpServerv4ExclusionRange -ComputerName $server -ScopeId $scope
Get-DhcpServerv4Reservation -ComputerName $server -ScopeId $scope
Get-DhcpServerv4OptionValue -ComputerName $server -ScopeId $scope
Get-DhcpServerv4Lease -ComputerName $server -ScopeId $scope |
  Select-Object -First 10 IPAddress, HostName, ClientId, AddressState

❯ View Expected Console Output

OptionId Name          Value
-------- ----          -----
3        Router        {192.0.2.1}
6        DNS Servers   {192.0.2.10, 192.0.2.11}
15       DNS Domain    {lab.example}

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03

Plan a Change Around the Subnet

Change Plan

Document the network ID, mask, usable pool, exclusions, reservations, lease duration, gateway, DNS servers, relay path, and rollback. For a new scope, validate that no other DHCP server serves the same subnet and that routing/relay is ready. Do not copy the sample values directly into a live network.

# Read the exact scope being changed immediately before the window.
Get-DhcpServerv4Scope -ComputerName $server -ScopeId $scope | Format-List *
Get-DhcpServerv4OptionValue -ComputerName $server -ScopeId $scope

❯ View Expected Console Output

Compare scope settings with the approved change record and address plan.

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04

Inspect Failover and Replicate Deliberately

High Availability

Windows DHCP failover shares IPv4 scope settings and lease state between two partner servers. Check the relationship before changing it. After editing a failover-enabled scope, replication is a separate operation; initiate it from the server whose settings should win because partner settings are overwritten.

Get-DhcpServerv4Failover -ComputerName $server

# After an approved scope change, replicate only that scope from the
# authoritative partner. Confirm the partner and scope ID first.
Invoke-DhcpServerv4FailoverReplication `
  -ComputerName $server `
  -ScopeId $scope `
  -Force

Get-DhcpServerv4FailoverStatistics -ComputerName $server

❯ View Expected Console Output

Review relationship state and confirm the intended scope is synchronized.

Caution

Failover replication copies configuration from the initiating server to its partner and overwrites the partner’s settings. Scope changes are not automatically replicated. Verify the authoritative server, partner, and scope IDs before running replication. Microsoft DHCP failover supports two Windows Server 2016 or later partners for IPv4 scopes; DHCPv6 scopes are not failover-enabled.

Tip

For a client-side validation, renew a test device’s lease during the approved window and inspect its assigned address, gateway, DNS servers, and DNS suffix. A lease alone does not prove the relay path or every scope option is correct.

Further reading: DHCP failover overview and Replicate DHCP failover settings.