What Every Engineer Should Know About TCP, Kernel Memory, and Load Balancers
This title could be clearer and more informative.Try out Clickbait Shieldfor free (5 uses left this month).
A deep dive into the systems concepts that distinguish senior from staff/principal engineers: kernel vs user space memory boundaries, DMA mechanics, the four-copy TCP data path, zero-copy via sendfile() and why TLS breaks it, TCP connection memory and file descriptor costs, and the fundamental architectural difference between L4 and L7 load balancers. L4 LBs use NAT to transparently forward packets while preserving client IPs; L7 LBs must terminate the TCP connection to read HTTP content, making a second connection to the backend unavoidable due to TCP sequence number negotiation. Kafka's high throughput and the existence of X-Forwarded-For headers are explained as direct consequences of these low-level mechanics.
