Changing vCenters IP address is only allowed if your vCenter use a FQHN like vcenter.home.local and not only a short name or a simple IP.
But about your questions. The vCenter IP will be stored in the vpxa.cfg on the ESXi and keep also in mind that vCenters IPs is stored in the vCenter Settings, together with vCenter ID, vCenter Name, vCenter IP) which also needs do be adjusted.
Regards,
Joerg
