zxdata

Notes on systems, networks and the boring parts in between.

Short write-ups from day-to-day work — packet captures, quic handshakes, cache invalidation, and the occasional postmortem of something that should not have broken.

Recent notes

Reading a TLS handshake in a packet capture
12 October 2026 · 9 min read
What actually happens when a prefix goes anycast
28 August 2026 · 12 min read
MTU, PMTUD and the 1500-byte lie
03 July 2026 · 7 min read

About

Infrastructure notes kept for personal reference, published in case they save someone an afternoon. Everything here is written from a laptop, usually late, occasionally wrong. Corrections are welcome by mail.

Contact: hello@zxdata.uk