Jason Yoder, MCT

Split-Scope DHCP allows you to have a redundant DHCP system on your network.  To achieve this in past implementations of Windows Server, we would allocate 80% of our address to one DHCP server and 20% to another.  This was referred to as the 80/20 rule.  To begin, you need to have the DHCP role installed on the two servers that will participate in the split.  On one server have the scope completely configured that you want to split. Open the DHCP console. Right click the scope that you want to split and then click Advanced –> Split-Scope . On the DHCP Split-Scope page, click Next . On the Additional DHCP Server window, enter the name of the second DHCP server and click Next . In the Percentage of Split screen, adjust the slider bar to set a percentage from the number of IP addresses that will be available on each server.  Click Next to continue. In the Delay in DHCP Offer screen, provide a response delay for the secondary server.  This...

In class we had a discussion on a slide that seems to present the time when a DHCP client at 87.5% of the lease period instead of 50%.  Below is an excerpt for TechNet that should help clear up the confusion.   Renewing a lease The DHCP client first attempts to renew its lease when 50 percent of the original lease time, known as T1, has passed. At this point, the DHCP client sends a unicast DHCPRequest message to the DHCP server that originally granted its lease. If the server is available, and the lease is still available, the server responds with a unicast DHCPAck message, and the lease is renewed. If the original DHCP server is available, but the client’s current lease is no longer available, the DHCP server responds with a DHCPNack message, and the client immediately starts the process to obtain a new lease. This can happen if the client has changed subnets or if the DHCP server cannot fulfill the lease request for some other reason. If there is no response from...