TCP or UDP
The two main ways to carry data: TCP, reliable and ordered, and UDP, light and without guarantees. How they work, their trade-offs, and how to choose for video, games, DNS or the web, up to QUIC and HTTP/3.
- 43 cards
- 3 topics
- Free
The outline, topic by topic
Each topic is weighted the way the exam weighs it.
- TCP
- UDP
- Choosing
A few cards from the deck
TCP: what is it?
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A connection-based transport protocol that delivers data reliably and in order
Reliability has a cost: a handshake at the start and waiting for resends on loss.
Opening a TCP connection: after “SYN” (Client → Server), what is the next message?
- ACK (Client → Server)
- First data (Client → Server)
- SYN-ACK (Server → Client)
- Data acknowledgement (Server → Client)
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SYN-ACK (Server → Client)
The server's sequence number, acknowledgement of the SYN. The server accepts and announces its own number.
Acknowledgement (ACK): what is it?
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The message by which the receiver confirms it got some data
Without an ACK after a delay, the sender sends the data again.
Opening a TCP connection: after “SYN-ACK” (Server → Client), what is the next message?
- SYN (Client → Server)
- First data (Client → Server)
- Data acknowledgement (Server → Client)
- ACK (Client → Server)
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ACK (Client → Server)
Acknowledgement of the SYN-ACK. Both sides know each other's numbers.