diff --git a/FastGithub.Scanner/GithubContext.cs b/FastGithub.Scanner/GithubContext.cs
index 3f233b7..dffefca 100644
--- a/FastGithub.Scanner/GithubContext.cs
+++ b/FastGithub.Scanner/GithubContext.cs
@@ -5,11 +5,26 @@ namespace FastGithub.Scanner
 {
     sealed class GithubContext : IEquatable<GithubContext>
     {
+        /// <summary>
+        /// 获取域名
+        /// </summary>
         public string Domain { get; }
 
+        /// <summary>
+        /// 获取ip
+        /// </summary>
         public IPAddress Address { get; }
 
-        public TimeSpan? HttpElapsed { get; set; }
+        /// <summary>
+        /// 获取或设置是否可用
+        /// </summary>
+        public bool Available { get; set; } = false;
+
+        /// <summary>
+        /// 获取或设置扫描总耗时
+        /// </summary>
+        public TimeSpan Elapsed { get; set; } = TimeSpan.MaxValue;
+
 
         public GithubContext(string domain, IPAddress address)
         {
@@ -19,7 +34,7 @@ namespace FastGithub.Scanner
 
         public override string ToString()
         {
-            return $"{Address}\t{Domain}\t# {HttpElapsed}";
+            return $"{Address}\t{Domain}\t# {Elapsed}";
         }
 
         public override bool Equals(object? obj)
diff --git a/FastGithub.Scanner/GithubContextCollection.cs b/FastGithub.Scanner/GithubContextCollection.cs
new file mode 100644
index 0000000..5c01444
--- /dev/null
+++ b/FastGithub.Scanner/GithubContextCollection.cs
@@ -0,0 +1,66 @@
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
+
+namespace FastGithub.Scanner
+{
+    sealed class GithubContextCollection
+    {
+        private readonly object syncRoot = new();
+        private readonly HashSet<GithubContext> contextHashSet = new();
+        private readonly Dictionary<string, IPAddress> domainAdressCache = new();
+
+        public bool Add(GithubContext context)
+        {
+            lock (this.syncRoot)
+            {
+                return this.contextHashSet.Add(context);
+            }
+        }
+
+        public GithubContext[] ToArray()
+        {
+            lock (this.syncRoot)
+            {
+                return this.contextHashSet.ToArray();
+            }
+        }
+
+        /// <summary>
+        /// 查找又稳又快的ip
+        /// </summary>
+        /// <param name="domain"></param>
+        /// <returns></returns>
+        public IPAddress? FindFastAddress(string domain)
+        {
+            lock (this.syncRoot)
+            {
+                // 如果上一次的ip可以使用，就返回上一次的ip
+                if (this.domainAdressCache.TryGetValue(domain, out var address))
+                {
+                    var key = new GithubContext(domain, address);
+                    if (this.contextHashSet.TryGetValue(key, out var context) && context.Available)
+                    {
+                        return address;
+                    }
+                }
+
+                var fastAddress = this.contextHashSet
+                    .Where(item => item.Available && item.Domain == domain)
+                    .OrderBy(item => item.Elapsed)
+                    .Select(item => item.Address)
+                    .FirstOrDefault();
+
+                if (fastAddress != null)
+                {
+                    this.domainAdressCache[domain] = fastAddress;
+                }
+                else
+                {
+                    this.domainAdressCache.Remove(domain);
+                }
+                return fastAddress;
+            }
+        }
+    }
+}
diff --git a/FastGithub.Scanner/GithubContextHashSet.cs b/FastGithub.Scanner/GithubContextHashSet.cs
deleted file mode 100644
index b96f419..0000000
--- a/FastGithub.Scanner/GithubContextHashSet.cs
+++ /dev/null
@@ -1,9 +0,0 @@
-using System.Collections.Generic;
-
-namespace FastGithub.Scanner
-{
-    sealed class GithubContextHashSet : HashSet<GithubContext>
-    {
-        public readonly object SyncRoot = new();
-    }
-}
diff --git a/FastGithub.Scanner/GithubScanService.cs b/FastGithub.Scanner/GithubScanService.cs
index e44c74b..a1d3d7d 100644
--- a/FastGithub.Scanner/GithubScanService.cs
+++ b/FastGithub.Scanner/GithubScanService.cs
@@ -14,7 +14,7 @@ namespace FastGithub.Scanner
     {
         private readonly GithubMetaService metaService;
         private readonly ILogger<GithubScanService> logger;
-        private readonly GithubContextHashSet results = new();
+        private readonly GithubContextCollection results = new();
 
         private readonly InvokeDelegate<GithubContext> fullScanDelegate;
         private readonly InvokeDelegate<GithubContext> resultScanDelegate;
@@ -30,6 +30,7 @@ namespace FastGithub.Scanner
             this.fullScanDelegate = pipelineBuilder
                 .New()
                 .Use<ConcurrentMiddleware>()
+                .Use<ScanElapsedMiddleware>()
                 .Use<PortScanMiddleware>()
                 .Use<HttpsScanMiddleware>()
                 .Use<ScanOkLogMiddleware>()
@@ -37,6 +38,7 @@ namespace FastGithub.Scanner
 
             this.resultScanDelegate = pipelineBuilder
                 .New()
+                .Use<ScanElapsedMiddleware>()
                 .Use<PortScanMiddleware>()
                 .Use<HttpsScanMiddleware>()
                 .Use<ScanOkLogMiddleware>()
@@ -58,12 +60,9 @@ namespace FastGithub.Scanner
             async Task ScanAsync(GithubContext context)
             {
                 await this.fullScanDelegate(context);
-                if (context.HttpElapsed != null)
+                if (context.Available == true)
                 {
-                    lock (this.results.SyncRoot)
-                    {
-                        this.results.Add(context);
-                    }
+                    this.results.Add(context);
                 }
             }
         }
@@ -71,15 +70,10 @@ namespace FastGithub.Scanner
         public async Task ScanResultAsync()
         {
             this.logger.LogInformation("结果扫描开始");
-            GithubContext[] contexts;
-            lock (this.results.SyncRoot)
-            {
-                contexts = this.results.ToArray();
-            }
 
+            var contexts = this.results.ToArray();
             foreach (var context in contexts)
             {
-                context.HttpElapsed = null;
                 await this.resultScanDelegate(context);
             }
 
@@ -88,19 +82,9 @@ namespace FastGithub.Scanner
 
         public IPAddress? FindFastAddress(string domain)
         {
-            if (domain.Contains("github", StringComparison.OrdinalIgnoreCase))
-            {
-                lock (this.results.SyncRoot)
-                {
-                    return this.results
-                        .Where(item => item.Domain == domain && item.HttpElapsed != null)
-                        .OrderBy(item => item.HttpElapsed)
-                        .Select(item => item.Address)
-                        .FirstOrDefault();
-                }
-            }
-
-            return default;
+            return domain.Contains("github", StringComparison.OrdinalIgnoreCase)
+                ? this.results.FindFastAddress(domain)
+                : default;
         }
     }
 }
diff --git a/FastGithub.Scanner/Middlewares/HttpsScanMiddleware.cs b/FastGithub.Scanner/Middlewares/HttpsScanMiddleware.cs
index 09119b6..6ceb89a 100644
--- a/FastGithub.Scanner/Middlewares/HttpsScanMiddleware.cs
+++ b/FastGithub.Scanner/Middlewares/HttpsScanMiddleware.cs
@@ -27,6 +27,8 @@ namespace FastGithub.Scanner.Middlewares
         {
             try
             {
+                context.Available = false;
+
                 var request = new HttpRequestMessage
                 {
                     Method = HttpMethod.Get,
@@ -40,13 +42,12 @@ namespace FastGithub.Scanner.Middlewares
                     UseProxy = false,
                 });
 
-                var startTime = DateTime.Now;
                 using var cancellationTokenSource = new CancellationTokenSource(this.options.CurrentValue.HttpsScanTimeout);
                 var response = await httpClient.SendAsync(request, HttpCompletionOption.ResponseHeadersRead, cancellationTokenSource.Token);
                 var server = response.EnsureSuccessStatusCode().Headers.Server;
                 if (server.Any(s => string.Equals("GitHub.com", s.Product?.Name, StringComparison.OrdinalIgnoreCase)))
                 {
-                    context.HttpElapsed = DateTime.Now.Subtract(startTime);
+                    context.Available = true;
                     await next();
                 }
             }
diff --git a/FastGithub.Scanner/Middlewares/ScanElapsedMiddleware.cs b/FastGithub.Scanner/Middlewares/ScanElapsedMiddleware.cs
new file mode 100644
index 0000000..382c37b
--- /dev/null
+++ b/FastGithub.Scanner/Middlewares/ScanElapsedMiddleware.cs
@@ -0,0 +1,26 @@
+using Microsoft.Extensions.DependencyInjection;
+using System;
+using System.Diagnostics;
+using System.Threading.Tasks;
+
+namespace FastGithub.Scanner.Middlewares
+{
+    [Service(ServiceLifetime.Singleton)]
+    sealed class ScanElapsedMiddleware : IMiddleware<GithubContext>
+    {
+        public async Task InvokeAsync(GithubContext context, Func<Task> next)
+        {
+            var stopwatch = new Stopwatch();
+            try
+            {
+                stopwatch.Start();
+                await next();
+            }
+            finally
+            {
+                stopwatch.Stop();
+                context.Elapsed = stopwatch.Elapsed;
+            }
+        }
+    }
+}
diff --git a/FastGithub.Scanner/Middlewares/ScanOkLogMiddleware.cs b/FastGithub.Scanner/Middlewares/ScanOkLogMiddleware.cs
index 3730642..18dfd16 100644
--- a/FastGithub.Scanner/Middlewares/ScanOkLogMiddleware.cs
+++ b/FastGithub.Scanner/Middlewares/ScanOkLogMiddleware.cs
@@ -17,7 +17,7 @@ namespace FastGithub.Scanner.Middlewares
 
         public Task InvokeAsync(GithubContext context, Func<Task> next)
         {
-            if (context.HttpElapsed != null)
+            if (context.Available)
             {
                 this.logger.LogInformation(context.ToString());
             }