DHCP Vendor Class Identifier: MSFT 50 vs. dhcpcd-5.5.6

Why the distinction matters

The DHCP (Dynamic Host Configuration Protocol) Vendor Class Identifier is a field in the DHCP request packet that identifies the type of device making the request. This information is used by DHCP servers to assign IP addresses and other network configuration settings to the device. Traditionally, Windows computers have used the Vendor Class Identifier "MSFT 5.0", while Android devices have used "dhcpcd-5.5.6".

Recent changes to the Vendor Class Identifier

Recently, Microsoft has updated the Vendor Class Identifier for some Windows-based devices to "MSFT 50". This change has caused some confusion, as it is now possible for both Windows and Android devices to have the same Vendor Class Identifier. So, how can you tell what type of device is making a DHCP request if the Vendor Class Identifier is the same?

The light cat icon

One way to tell the difference is by looking at the light cat icon that is displayed next to the device name in the DHCP server's client list. The light cat icon indicates that the device is a Windows-based device. If the light cat icon is not displayed, then the device is likely an Android device.

Process of assigning IP addresses to DHCP clients

As described above, the value of the DHCP Vendor Class Identifier option is only sent to clients that have a specific vendor class (e.g., MSFT 50 in the example). The administrator configures the DHCPv4 server to send Vendor-specific Options to the client. The DHCPv4 client joins the network and sends a DHCP request packet to the DHCPv4 server. The DHCPv4 server responds with a DHCP offer packet that includes the Vendor-specific Options. The DHCPv4 client accepts the offer and sends a DHCP request packet to the DHCPv4 server to request an IP address. The DHCPv4 server assigns an IP address to the DHCPv4 client.