Using distant or heavily throttled upstream DNS servers.
But note: higher timeouts worsen queueing under failure.
V2Ray routes DNS queries through the proxy unnecessarily.
Standard DNS uses UDP. If V2Ray forces UDP traffic to wrap inside a heavy TCP proxy connection, resolution speeds plummet. Step 1: Diagnose the DNS Bottleneck v2ray slow dns server
In transparent proxy scenarios, DNS requests from clients are not automatically captured unless you manually apply iptables or nftables rules to redirect UDP port 53 traffic to a local DNS resolver like V2Ray's internal DNS.
Are you experiencing slowness on or just specific ones?
If you're running a router-based proxy or a transparent proxy for your entire network, review your domainStrategy setting: Using distant or heavily throttled upstream DNS servers
Some ISPs rate-limit DNS queries to non-default resolvers, causing artificial delays or TCP fallback.
Run these commands from your server/PC (replace 1.1.1.1 with your V2Ray upstream DNS):
Return to the home screen and tap "Connect." 3. Advanced V2Ray Internal DNS (Optional) Standard DNS uses UDP
Sometimes the DNS server is fine, but the V2Ray VPS node itself has high ping. Switch nodes to isolate whether the lag is caused by the proxy server or the DNS setup.
Domain-based routing rules (e.g., "domain:google.com" → "proxy" ) require resolution before decision. If DNS times out, V2Ray may fall back to a default route or drop the connection.
If the standard methods aren't enough, consider these advanced approaches.
By default, most V2Ray setups use a split routing strategy (freedom for domestic traffic, proxy for international). For this to work, V2Ray must resolve a domain name to an IP address before deciding where to send the packet.