Assuming standard $1500$ byte Ethernet max payloads: how many IPv$4$ fragments will be needed to transfer $2000$ bytes of user data with a single UDP send? And, how do the $2000$ bytes get split over the frags?

Despite its conceptual elegance, RPC $($Remote Procedure Call$)$ has a few problems. Discuss any $3$ of those in brief.

Why is timestamping needed in real$-$time applications? This is in the context of Real$-$time Transport Protocol $($RTP$).$

Why does UDP exist? Would it not have been enough to just let user processes send raw IP packets?

Explain how QUIC eliminates a couple of RTTs usually needed at the start of a secure web connection.