https://blog.etcnotes.top/Recent content on 我的笔记Hugozh-cnThu, 24 Sep 2026 00:00:00 +0000https://blog.etcnotes.top/docs/network/tcp/Thu, 24 Sep 2026 00:00:00 +0000https://blog.etcnotes.top/docs/network/tcp/<h1 id="tcp-三次握手">TCP 三次握手<a class="anchor" href="#tcp-%e4%b8%89%e6%ac%a1%e6%8f%a1%e6%89%8b"></a></h1> <blockquote class="book-hint info" > **流程**：客户端 SYN → 服务端 SYN+ACK → 客户端 ACK。 </blockquote> <ol> <li>客户端发送 <code>SYN=1, seq=x</code></li> <li>服务端回复 <code>SYN=1, ACK=1, seq=y, ack=x+1</code></li> <li>客户端回复 <code>ACK=1, ack=y+1</code></li> </ol> <blockquote class="book-hint warning" > 为什么要三次？为了确认双方收发能力都正常，防止历史连接请求造成误连。 </blockquote> <p>参考 <a href="https://blog.etcnotes.top/docs/network/http/">HTTP 基础</a> 笔记里的抓包示例。</p>https://blog.etcnotes.top/docs/linux/commands/Thu, 24 Sep 2026 00:00:00 +0000https://blog.etcnotes.top/docs/linux/commands/<h1 id="常用命令">常用命令<a class="anchor" href="#%e5%b8%b8%e7%94%a8%e5%91%bd%e4%bb%a4"></a></h1> <div class="highlight"><pre tabindex="0" style="color:#e2e4e5;background-color:#282a36;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-bash" data-lang="bash"><span style="display:flex;"><span><span style="color:#78787e"># 查看磁盘占用</span> </span></span><span style="display:flex;"><span>du -sh * | sort -h </span></span><span style="display:flex;"><span> </span></span><span style="display:flex;"><span><span style="color:#78787e"># 查看端口占用</span> </span></span><span style="display:flex;"><span>ss -tulpn </span></span><span style="display:flex;"><span> </span></span><span style="display:flex;"><span><span style="color:#78787e"># 找大文件</span> </span></span><span style="display:flex;"><span>find / -type f -size +100M 2&gt;/dev/null</span></span></code></pre></div>https://blog.etcnotes.top/docs/%E6%95%B0%E6%8D%AE%E5%BA%93/mysql-index/Sun, 20 Sep 2026 00:00:00 +0000https://blog.etcnotes.top/docs/%E6%95%B0%E6%8D%AE%E5%BA%93/mysql-index/<h1 id="mysql-索引">MySQL 索引<a class="anchor" href="#mysql-%e7%b4%a2%e5%bc%95"></a></h1> <blockquote class="book-hint info" > InnoDB 使用 B+ 树索引，叶子节点存数据，非叶子节点只存键值。 </blockquote> <h2 id="常见类型">常见类型<a class="anchor" href="#%e5%b8%b8%e8%a7%81%e7%b1%bb%e5%9e%8b"></a></h2> <div class="book-tabs" > <input type="radio" class="toggle" name="tabs-1" id="tabs-1-0" checked="checked" /><label for="tabs-1-0">主键索引</label><div class="book-tabs-content markdown-inner"> 聚簇索引，叶子节点即数据行。</div> <input type="radio" class="toggle" name="tabs-1" id="tabs-1-1" /><label for="tabs-1-1">二级索引</label><div class="book-tabs-content markdown-inner"> 叶子节点存主键值，回表才能取到整行。</div> <input type="radio" class="toggle" name="tabs-1" id="tabs-1-2" /><label for="tabs-1-2">联合索引</label><div class="book-tabs-content markdown-inner"> 遵循最左前缀原则。</div> </div> <h2 id="示例">示例<a class="anchor" href="#%e7%a4%ba%e4%be%8b"></a></h2> <div class="highlight"><pre tabindex="0" style="color:#e2e4e5;background-color:#282a36;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-sql" data-lang="sql"><span style="display:flex;"><span><span style="color:#78787e">-- 联合索引 (a, b, c) </span></span></span><span style="display:flex;"><span><span style="color:#ff6ac1">CREATE</span> <span style="color:#ff6ac1">INDEX</span> idx_abc <span style="color:#ff6ac1">ON</span> t (a, b, <span style="color:#ff6ac1">c</span>); </span></span><span style="display:flex;"><span> </span></span><span style="display:flex;"><span><span style="color:#78787e">-- 能走索引: a、a+b、a+b+c </span></span></span><span style="display:flex;"><span><span style="color:#78787e">-- 不能单独走: b、c</span></span></span></code></pre></div><details ><summary>为什么不建议 SELECT *</summary><div class="markdown-inner"> 会破坏覆盖索引，导致回表，且传输多余字段。 </div></details>https://blog.etcnotes.top/docs/network/http/Thu, 24 Sep 2026 00:00:00 +0000https://blog.etcnotes.top/docs/network/http/<h1 id="http-基础">HTTP 基础<a class="anchor" href="#http-%e5%9f%ba%e7%a1%80"></a></h1> <p>常见方法：</p> <div class="book-tabs" > <input type="radio" class="toggle" name="tabs-1" id="tabs-1-0" checked="checked" /><label for="tabs-1-0">GET</label><div class="book-tabs-content markdown-inner"> 请求资源，幂等。</div> <input type="radio" class="toggle" name="tabs-1" id="tabs-1-1" /><label for="tabs-1-1">POST</label><div class="book-tabs-content markdown-inner"> 提交数据，非幂等。</div> <input type="radio" class="toggle" name="tabs-1" id="tabs-1-2" /><label for="tabs-1-2">PUT</label><div class="book-tabs-content markdown-inner"> 整体替换资源。</div> </div> <details ><summary>状态码速查</summary><div class="markdown-inner"> - 2xx 成功 - 3xx 重定向 - 4xx 客户端错误 - 5xx 服务端错误 </div></details>https://blog.etcnotes.top/docs/mind/mind/Thu, 24 Sep 2026 00:00:00 +0000https://blog.etcnotes.top/docs/mind/mind/<h1 id="mind">mind<a class="anchor" href="#mind"></a></h1> <p>mind</p>https://blog.etcnotes.top/docs/network/dns/Sun, 20 Sep 2026 00:00:00 +0000https://blog.etcnotes.top/docs/network/dns/<h1 id="dns-解析过程">DNS 解析过程<a class="anchor" href="#dns-%e8%a7%a3%e6%9e%90%e8%bf%87%e7%a8%8b"></a></h1> <blockquote class="book-hint info" > 递归查询 vs 迭代查询：客户端问本地 DNS（递归），本地 DNS 逐级问根/顶级/权威（迭代）。 </blockquote> <ol> <li>浏览器缓存 → 系统 hosts → 本地 DNS 服务器</li> <li>本地 DNS 依次查询：根域名服务器 → <code>.com</code> 顶级域 → 权威域名服务器</li> <li>拿到 IP 后逐级缓存并返回</li> </ol> <h2 id="常用命令">常用命令<a class="anchor" href="#%e5%b8%b8%e7%94%a8%e5%91%bd%e4%bb%a4"></a></h2> <div class="highlight"><pre tabindex="0" style="color:#e2e4e5;background-color:#282a36;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-bash" data-lang="bash"><span style="display:flex;"><span>dig +short example.com </span></span><span style="display:flex;"><span>dig @8.8.8.8 example.com A </span></span><span style="display:flex;"><span>nslookup example.com</span></span></code></pre></div><details ><summary>TTL 是什么</summary><div class="markdown-inner"> TTL 决定这条记录在各层 DNS 缓存里能存活多久，单位秒。改解析后没生效，通常是缓存还没过期。 </div></details>