In May 2017, over 300,000 computers worldwide were infected by a ransomware called Wannacry. The wide spread nature of the attack was a major concern, in spite of this, the attack did not have long term effects and not a lot of money was made by the hackers.
Cloud computing is essentially when information and programs are stored and can be accesses over the internet. The idea of cloud computing has been around since the sixties. It is said to have been created by Joseph Carl Robnett Licklider as he worked on the ARPNET (which was the name of the internet in its first stages), but the word has evolved over the years, the idea of cloud computing now is very different from what it was back then.
The DNS server stores the IP addresses of website's URL, the internet works with IP addresses so when you request to go to a website you type in the URL, the computer requests the DNS server for the IP address associated with the URL wanted by the user.
The NAT solves the issue of there being too many people using the internet and not enough IP addresses for everyone. It allows for many computers connected to the same router to share the same public IP address, by assigning each device connected to the router with a unique private IP address.