How to determine IP type - DHCP/Static/MAC Reservation

Started by Brandon

Brandon

How to determine IP type - DHCP/Static/MAC Reservation   13 October 2023, 10:18

Hello! I've been using your products for a few years now and have found that it is the best product on the market. I love the ability to get deep information with extreme ease.

I do have one question or possibly a request. Is it possible to determine if a device is a DHCP client, self-assigned Static, or using a MAC Reservation?

Thank you for your time and consideration.
SoftPerfect Support forum - Ann avatar image
Ann

Re: How to determine IP type - DHCP/Static/MAC Reservation   13 October 2023, 13:02

Unfortunately, there is no standardized method for determining whether a specific device has obtained its IP address from a DHCP server, is configured with a static IP address, or is using an IP address reserved for its MAC address.

In general, there are two potential sources of information for this:
  1. DHCP Server Lease Tables
    One approach is to check the DHCP server lease tables. This involves querying the DHCP server for its lease tables and then comparing each device's IP address with these tables. If a specific IP address is not found in the tables, it is likely statically assigned. However, it's important to note that there is no universal standard for querying lease tables from a DHCP server. The method for doing so would depend on the specific DHCP server software used in your network.
  2. Device Self-Knowledge
    Devices often have knowledge of how they obtained their IP address. They can typically distinguish between receiving an IP address from a DHCP server and being configured with a static IP address. However, devices are usually unaware of whether the IP address is reserved for their MAC address or not. From the device's perspective, it either consistently receives the same IP address from the DHCP server (which often indicates reservation based on MAC address) or different IP addresses each time (typically indicating regular DHCP assignment).

It's important to consider that devices vary widely in terms of their capabilities and the information they can provide about their IP configuration. Therefore, the feasibility of obtaining this information directly from devices may vary.

It would be helpful to know which DHCP server your network is using. Depending on the specific DHCP server software in use, there may be a way to access its lease tables. If such access is possible, we could explore the feasibility of implementing this type of IP assignment method identification within our Network Scanner.

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