A small library has an integrated switch and router that is not wireless. All of the public PCs in the library are connected to the device. Which of the following is the FIRST thing the library should do to deter curious patrons from interfering with the device?
A. Configure DNS to resolve externally rather than internally
B. Enable MAC filtering to permit public PCs
C. Change the default user name and password
D. Set up the DHCP server to use a different gateway option