I don't exactly know WHY, but I can guess..
I think it's because, if you're writing, you can know where the source is from if you print the WHOLE SCREEN, or just to remember what the electronic source says.
Answer:
The ledgers are secure, shared, and incorruptible is the correct answer.
Answer:
DNS or Domain Name System
Explanation:
You can query a DNS server with a domain name to get an IP address.
Answer:
It is the very last statement (bottom). Also copied to the the client
Explanation: