TLD stands for Top Level Domain. The domain like .com, org, .in, .au are known as the Top level domain because after querying the root server, the DNS queries the Top Level Domain server to resolve the full domain name.
This is the acronym for Time to Live. As the name suggests, this term is used to specify the expiry of the packet which means that after how many hops, a particular packet will get destroyed. When a packet is sent across the internet, at each hop the TTL of packet decrease by one. Different operating systems produce packets with different TTL.