sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder Use code with caution. Summary Troubleshooting Checklist Root Cause Immediate Fix High latency on all websites UDP Throttling by ISP Switch server address to an HTTPS link (DoH) Local sites load very slowly Domestic traffic routed to foreign DNS Add a local DNS server using geosite:cn rules Delayed connection spikes Conflicting routing strategies Set domainStrategy to IPIfNonMatch
Your local system resolves the domain, and then the V2Ray server resolves it again upstream. This doubles your latency.
The DNS protocol was never designed for high-volume data transfer. It has a small maximum packet size, leading to high overhead and significant latency. Step-by-Step: Creating and Setting Up a Slow DNS Server 1. Generate Your Server Credentials
The key insight to remember: . If your foundation is slow or broken, nothing else matters. Get DNS right first, and everything else will follow.
Enable verbose logging in V2Ray to see what's happening during DNS resolution: v2ray slow dns server
: If you experience "Slow DNS lookup" errors, try clearing your app cache or DNS cache. Server Distance
To achieve lightning-fast connection speeds, you need to optimize your V2Ray configuration file ( config.json ). Follow these proven optimization steps. Step 1: Implement Split DNS (The Best Solution)
Using a tool like nslookup or dig , manually query a few reputable public DNS providers from your command line to measure their response times.
The root cause of slow DNS is almost always one of three scenarios: The DNS protocol was never designed for high-volume
Many users test their proxies by going to a "DNS Leak Test" website.
V2Ray relies on internal databases to categorize local vs. international websites. If these files are outdated, V2Ray will send local websites to the slow foreign DNS server. Download the latest routing files weekly.
"address": "223.5.5.5", "domains": ["geosite:cn"] ,
This typically points to domainStrategy: IPOnDemand causing unnecessary resolutions, or an upstream DNS server with high latency. Run dig commands to measure actual response times from your configured resolvers. Generate Your Server Credentials The key insight to
. This method is typically used when other ports are blocked, but it is inherently slower than standard VMess or VLESS protocols because it wraps data within DNS queries. 1. Understanding "Slow DNS" in V2Ray In this context,
One critical clue is when the exact same server configuration works flawlessly on a mobile client but fails on a desktop. This strongly suggests the issue is not with the server or network, but specifically with the client's interaction with the operating system.
The term "Slow DNS" is literal. The process of encapsulating packets into DNS queries is naturally slower than direct tunneling. However, if the experience is painfully slow, it is likely due to one of these factors:
The most straightforward cause of slow DNS resolution is simply using a DNS server that is geographically distant or congested. When you configure V2Ray to use 8.8.8.8 (Google DNS) while physically located in Asia or Europe, every DNS query travels across continents before returning.
If you're using GUI clients like v2rayA or v2rayNG, check for DNS optimization features built into the client. v2rayA offers five anti-pollution modes, including DNS Forward (queries through proxy) and DoH (DNS over HTTPS) options. Earlier versions had known issues with all-DoH configurations causing slow lookups, but these have since been fixed.
Return to the home screen and tap "Connect." 3. Advanced V2Ray Internal DNS (Optional)