DHCP Lease Vs Own?

We had an interesting debate at work about exactly how DHCP works and who holds the lease / IP address.

Understanding you can set ranges for which addresses are in a dhcp pool and which are static. With that said - I would like your take of how the following would work. This may be in another discussion but was unable to find exact answer.

I have a dual NIC server set to static on client network side and static on camera side. The client changes their IP network scheme and our server no longer communicates to the external network due to diff subnet / ip range. I switch from static to DHCP to find their new network range. Once a DHCP address is assigned to the NIC with new IP range and subnet then we take that exact address and make it static.

Who owns the rights to that address. The router has a table saying yes - this MAC address on this NIC owns this IP address. Does the server set the lease or does the router retake address back and add it to the pool when it decides. When running ipconfig you can see the lease time, understood.. Does IT have to designate me that IP address from the DHCP pool or will router "know" that IP address is no longer available because it hasn't given it back. Will the router automatically assign that address to another device even though there is a MAC address with associated DHCP address running through it's ports?

I recently attended a training / multi-vendor class and had two claim that you can take the DHCP IP address that was given to you and make it static with no issues or conflicts. Any ideas or references to articles. Thank you.

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*'* ***** **** ** ********* **** *********, ****if *** **** ****** ** ********* *** **** ****** ** *** **** ******* **** ****** ** ******* ** ******, it is generally preferable to keep all devices dynamic and assign reservations to them so that changes like gateway, DNS, etc. can propagate automatically. Note the bolded text, though: if you don't have the ability to update the DHCP server, or have it updated as needed, you could run into a problem in the process of setting things up.

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**.**.*.** *** .** *** *** *** ****/**** (**** ***** *** two)
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**.**.*.** **** ** *** *** ***** *****
**.**.*.** **** ** *** *** ******* ******** (**** ***** **** have ***)
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**.**.*.** **** ** *** ****** ******* ******
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**.**.*.*** **** *** *** ******* ** *** ****** ***/***

*** ******* *** ********** ********, **** *** **** **** ***** there ****** *** ******* ***** ** ******* **** ******* ** DHCP (******** ** ******* *** **** **** **** ******).

***** ******/********** ***** **** ***** *** ********* ***** ** ****.

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