rdfile /etc/rc is a command used for reading the contents of the system file \etc\rc. Startup commands for your storage system are stored in the /etc/rc file. The /etc/rc file contains commands that the storage system executes at boot time to configure the system.
Refer 165 page in the attached document for more information.
BY common sense I can figure out that RC stands for Running configurations..
Any new changes needed on the filer configuration - be it options ,vlan additions,routed etc need to be updated here.
Note that if you want the changes to take effect - you need to re-read the RC file once again or else it will not show up on the filer.
Two ways of bringing the new configuration into effect - either reboot the node where you have done the changes ("reboot" command or NDU TO/GB ) and second one is using "source" command which will bring the changes into effect immediately.