Option 125 in DHCP packet which is used along with Netsight is ideally supposed to be superseded by ZTP+ in XMC.
Option 43 works for cases where there is no XMC, i.e. the config/xsf/python files' location is provided over these options so that ZTP can happen without use of XMC/Netsight.
However, due to a software bug, this fallback to old ZTP does not happen if ZTP+ fails. CR xos0070318 is created to solve this issue.