To ensure that RFC3442-standard classless static routes provided by a DHCP server are processed correctly when using NetworkManager, the following lines should be placed into the /etc/dhclient.conf file or, if using per-interface DHCP options, the /etc/dhclient-<ifname>.conf file:
option rfc3442-classless-static-routes code 121 = array of unsigned integer 8;
option ms-classless-static-routes code 249 = array of unsigned integer 8;
also request rfc3442-classless-static-routes;
also request ms-classless-static-routes;
The above lines will ensure that RFC3442 classless static routes are requested from the DHCP server, and that they are properly processed by NetworkManager.
