DHCP option 82
DHCP option 82 contains parameters that can be set by the DHCP server and delivered to the DHCP client. Option 82 contains DHCP relay agent information.
Links:
https://datatracker.ietf.org/doc/html/rfc3046
https://networklessons.com/switching/dhcp-snooping
https://networklessons.com/cisco/ccie-routing-switching/cisco-ios-dhcp-relay-agent