Numbers To Know medium
How many Round Trips (RTT) does a standard TLS 1.2 handshake add *before* the first HTTP byte is sent?
- A 0 RTT (No extra delay)
- B 1 RTT
- C 2 RTTs
- D 5 RTTs
Answer: C. 2 RTTs
In TLS 1.2, a secure connection requires 'chatter' between the client and server before any real data can be sent. After the initial TCP handshake (1 RTT), the TLS 1.2 handshake requires 2 additional Round-Trips to exchange certificates and agree on encryption keys. This means for a user in Australia accessing a server in London (~300ms RTT), they must wait nearly 1 full second (3 RTTs) before they even see the first byte of the website! Modern TLS 1.3 was designed specifically to fix this, cutting the handshake down to 1 RTT and even supporting a '0-RTT' mode for returning visitors to eliminate this setup delay entirely.
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