structure padding and packing:

Structure is of user defined data types, Could be with the different combination of data types. When structure is defined with different data types, this data types aligned with padding to its natural boudaries of data, to reduce the CPU cycles.

struct sample {

char a;

char b;

int c;

}

If structure padding is not there to read an int variable it takes 2 CPU cycles, where as with structure padding it takes a single cycle.

cloudfare:

Is the world wide cloud reverse proxy, which helps in hiding the webservers IP from the web browser. 

In b'wn the webserver and web browser and hides the webservers IP addresses. Hence the DoS attacks can be avoided at the webserver. With somehow at the reverse proxy the DosAttacks are avoided.