The value of tmnxLudbRadproxCacheMatchOption specifies
in what DHCP option to retrieve the value to be used
as lookup key in the RADIUS Proxy cache.
The value of tmnxLudbRadproxCacheMatchOption is only relevant
if the value of tmnxLudbRadproxCacheMatchType is equal to 'option'.
The value zero means that this object is not configured.