# Technotes

- [TCP Fast Open](/surge-knowledge-base/technotes/tfo.md)
- [HTTP Protocol Version](/surge-knowledge-base/technotes/http-protocol-version.md): This document summarizes the differences between various HTTP protocol versions, as well as the impact of Surge activation on HTTP protocol versions.
- [Local and Proxy DNS Resolution](/surge-knowledge-base/technotes/dns.md)
- [Testing Strategy for Automatic Policy Groups](/surge-knowledge-base/technotes/testing-group.md): The testing strategy for Surge's automatic policy group is quite complex. This document provides a detailed description of the design behavior and rationale under various circumstances.
- [Differences between REJECT Policies](/surge-knowledge-base/technotes/reject.md)
- [User Agent Rules](/surge-knowledge-base/technotes/user-agent.md)
- [NAT Types](/surge-knowledge-base/technotes/nat-type.md)
- [IPv6 RA Override](/surge-knowledge-base/technotes/ipv6-ra.md)
- [VM UDP Fast Path](/surge-knowledge-base/technotes/udp-fast-path.md)