Where will the DHCP subnet be obtained from if there is a two NSG devices with a Site-To-Site VPN?

[Deleted User]

The client still use the local LAN subnet to communicate with the peer site, so it won't get the IP from the peer site DHCP server.

For instance, there are 2 NSG connected with site-to-site VPN as like the following topology. The client under NSGA is still using LAN1 subnet 192.168.10.0/24 to communicate with LAN2 subnet 192.168.20.0/24.

LAN1--(192.168.10.0/24)NSG(A)===VPN===NSG(B)--LAN2(192.168.20.0/24)