Questions

IP address is currently 4 bytes long. An IP address is written in "dotted decimal" notation, which is 4 sets of numbers separated by period each set representing 8-bit number ranging from (0-255).

Wherever on earth we hold a compass, the needle points towards the magnetic North Pole. A compass is a great tool for navigation.

Compass is widely used in aircrafts, ships, military services,...

Razakars

DRAM is a Volatile random-access memory (VRAM).

Volatile random-access memory (VRAM) is random-access memory that retains its information when power is turned on.

Examples of volatile memory are primary storage (typically dynamic RAM, DRAM), and fast CPU cache memory (typically static RAM, SRAM, which is fast but energy-consuming and offer lower memory capacity per area unit than DRAM).

Non-volatile random-access memory (NVRAM) is random-access memory that retains its information when power is turned off.

Examples of non-volatile memory are flash memory (used as secondary memory) and ROM, PROM, EPROM and EEPROM memory (used for storing firmware such as BIOS). 

It is ABACUS.

Words formed are as below 

BUS
CAB
CUB
US