You can use SmartPort macros to enable features and settings based on the location of a switch in the network and for mass configuration deployments across the network. Each SmartPort macro is a set of CLI commands that you define.
The metal with the highest melting point is Tungsten (W) at 3410 degrees Celsius (6170 degrees Fahrenheit). However, technically Carbon has a higher melting point, though not under normal atmospheric conditions. This is because it sublimates (turns directly from a solid to a gas) at 6740 degrees Fahrenheit under normal circumstances.
MgO will have the highest melting point. They are all ionic compounds, so the melting point is determined by the charge densities of the ions (a large charge density is a big charge in a small space). Between Na+ and Mg2+, the magnesium ion will have the highest charge density because it is the smaller ion.