How to configure DHCP Failover Active/Passive (Hot-Standby Mode) and Failover Load Balance Mode in Windows 2012 R2

There are two types of DHCP Failover relations –

  1. Load Balance mode which provides Active-Active configuration and
  2. Hot Standby mode which provides Active-Passive configuration

Load balance mode: if the two server is configured in this mode both the DHCP servers respond to client requests and load balance the requests between them based on an admin specified load distribution ratio such as 50-50 in default configuration.

Hot-Standby mode: aka (Active-Passive), only one of the servers actively leases IP addresses and option configuration to clients in given subnet(s)/scope(s) while the other server (standby) is passive. The standby server services the clients, only in event of active server being down. The clients fallback to the active server once the active server becomes available again post the outage.

The Load balance mode is more suited for single site deployment where the 2 DHCP servers in a failover relationship are co-located with the subnets/scopes being served by them. As the servers are in network proximity with the clients, the clients do not experience any latency while acquiring or renewing an IP address.

Hot-Standby mode is more suited for multi-site deployment topologies. Each site would have a local DHCP server which is configured to provide the DHCP service to the clients on the local network and DHCP server at a remote site would be standby server. In a normal state of operation, computers and devices on a given site receive IP addresses and other network configuration from the DHCP server located at the same site as the clients. However, in the event of the local DHCP server being down, the DHCP server from the remote site would provide the service to the clients. source:

In this article we will focus on the Hot-Standby mode aka (Active-Passive)

Step 1: Open the Server Manager of Server01 and click the “Add roles and features” and then select the “DHCP Server” Dynamic Host Configuration Protocol Server role this will enable you to centrally configure, manage and provide temporary IP addresses and related information for client computers.

Things to note :
> You should configure at least one static IP address on this computer.
> Before you install DHCP server, you should plan your sunets, scopes, and exclusions. Store the plan in a safe place for later reference.

Server IP assignement:

Server01 -> WIN2012R2T2 – IP: 10.20.30.52
Server02 -> WIN2012R2T3 – IP: 10.20.30.53
Desktop   -> TEST-DESKTOP – IP: 10.20.30.xx

 

 

Step 2: The DHCP allow servers to assign or lease IP addresses to compuers and other devices that are enabled as DHCP Clients. Deploying a DHCP serer on the network provides computer and other TCP/IP based network devices with valid IP addresses and the additional coniguration parameters these devices need called DHCP Options. This allowes computers and devices to connect to other network resources such as DNS servers, WINS server and Routers.

In this Windows just click next no need to select anything.

Optional features such as administration tools might be displayed on this page because they have been selected automatically and if ever you want to not include this feature you need to click the previous button and clear their checkboxes.

Once its completed you will see this below screenshot and need to further configure the settings of the DHCP service.

Step 3: The following steps will be performed to complete the configuration of the DHCP server on the target computer. Create the following security groups for delegation of DHCP server Administration

> DHCP Administrators
> DHCP Users

Then reboot your server.

Note: Do the same for SERVER02 to enable the DHCP role after that proceed to Step 4

Step 4:  Open the DHCP Windows manager and  then right click the “IPv4” and create “New Scope…”

In this wizard create the SCOPE name make sure its relevant to your network assignment if your configuration multiple VLANs then change this name accordingly.

Step 5: You need to define the scope address range in this below window wizard. I’m using IP block 10.20.30.0 /24 or 255.255.255.0 and I will configure to assign only 10.20.30.150-10.20.30.200 for DHCP

Add exclusions if there’s any reservation of the IP bock scope assigned earlier. This can be use for example for Printer, Fax Machine, or management IP.

 

Step 6: In this wizard we can configure what will be the lease time duration or how long a client can use an IP address from this scope.

For this article I will be choosing 1 day. Lease duration should typically be equal to the average time the computer is connected to the same physical network. for mobie network that consist mainly of portable computer a more shorter lease duration can be useful. Likewise, for a stable network that consists mainly of desktop computers at fixed location, longer duration are more appropriate.

Step 7: In this step we might want to configure the options that we going to use for this scope to work such as the DNS IP, WINS and IP Gateway of client desktop machine.

Choose “Yes, I want to configure these options now” and click next

Step 8: To add an IP address for router aka gateway that the client will be using type it here then click “Add” usually this are the .1 or .254 in your environment.

and the DNS that the client will going to use.

This is optional however if you have Active Directory running it usually enabled that is where your WINS server.

Step 9: Now that all the configuration is in place we need to activate this by selecting “Yes, I want to activate this scope now” as shown in below screenshot.

 

Phase 2 >>

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