In essence, Without it, AdGuard VPN would not know where to connect or how to optimize your traffic.

Therefore, tb-rg.adguard.net translates to: The Test Routing Gateway endpoint within the AdGuard technical network.

When you use https://dns.adguard.net/dns-query , your requests are routed through a reverse proxy. That proxy uses dynamic subdomains internally to track sessions, apply rate limiting, and log without storing IP addresses. A DoH request might be rewritten to: