Old DHCP client won't go away fake-for-negative-caching.adguard.com

[yyzguy]

I replaced a client device. I want to use the original hostname for the replacement. However, the original hostname still seems to be somewhere in AGH, but it does NOT show up in DHCP leases.

When I do an nslookop with debug, one of the lines is fake-for-negative-caching.adguard.com
`
The original device has been offline for much longer than the DHCP lease time. I see no record of it anywhere in the GUI. Is there some other way to clear it out?

As a workaround, i gave the replacement device a new hostname, but that's not a long term solution as I would like to rely on the original name resolving to the replacement device.