域名是一个网站的门面，也是最容易被攻击的一个环节，所以保护好自己的域名至关重要。
注：国内备案域名以下的情况会很少很少，多常见于境外 IP。
Domain name abnormalities are classified into various behaviors such as being blocked, contaminated, hijacked, and disabled by operators. The following are some of the most common abnormalities:
❗️ By the wall
There must be a reason why the domain name was blocked, and the possibility of being pulled into the GFW blacklist and released is very slim. Confirm that your site content does not contain illegal content.
预防被墙，确认没有非法内容的前提下，可以多弄些域名用引导页分发、或者从技术角度把爬虫全部拦死。
可以尝试做 301 跳转，将老的域名永久跳转到新的域名，有专门做这种 301 跳转，价格昂贵。
❗️ contaminated
This has nothing to do with the content of the site. The abnormality is that querying the resolution of your own domain name will have a bunch of messy resolution records that you don't know, and the content you visit is not the content of your own site (generally illegal content). At present, it is known that the risk of buying domain names in GoDaddy and Cloudflare is very high (not listed does not mean certain security), and purchasing their advanced services may be protected, but if you don't buy it, it is strongly recommended to configure DNS resolution to domestic big factories such as Tencent dnspod (recommended) or Ali Wanwang. Domestic big factories are protected by default.
预防污染，建议把 DNS 解析迁回国内，有能力的可以买高级服务，开启 DNSSEC。
一旦被污染很难回去，现在市面上有一些办法可以把污染清洗掉，价格昂贵。
❗️ Unlawfully abducted
Hijacking is divided into two types: one is DNS hijacking, which occurs in the cloud. The behavior is to visit one's own website and jump to another domain name or inexplicable pop-up advertisements, which will affect a large number of users. One is that it occurs in the customer's local area, downloading an APP from an informal channel, accessing something that should not be accessed, etc., with a virus, and tampering with the browser. If it is the second type, it will only occur on the customer's personal device, which does not affect others. It can be solved by changing the browser, resetting the system, etc. If it is the first type, it is similar to being polluted, and it is generally difficult to solve. There are black technologies on the market that seem to be able to solve it,
预防 DNS 劫持，建议把 DNS 解析迁回国内，有能力的可以买高级服务，开启 DNSSEC。
❗️ Banned or hijacked by the operator
The more famous ones are mobile shielding, wall-in-wall, GFW is not wall but mobile wall. A CDN set may not solve the problem 100%. Determining that it is disabled is a very complicated process. It can only be said that you can give it a try. And it is divided into IP wall and domain name wall just like being walled. You need to confirm it before finding a way.
地方运营商禁用，如"电信泉州"，常年无法访问，这个无解。或者某些地区会时常出现短期解析到 0.0.0.0 或者解析失败等错误，都可能是当地运营商拦截，一般会恢复， 可以使用网络拨测工具查看解析情况。
预防运营商禁用，做好反爬虫肯定没错，运营商也不会无缘无故去禁用，保证站内无非法内容。
❗️ Jump to the anti-fraud page
- The operator intercepts and jumps to the anti-fraud page, and a red screen will appear when the page is opened. Especially China Unicom in some regions.
- Regional interception jump anti-fraud page, currently common in Jiangsu - Suzhou, will jump to Jiangsu unique anti-fraud page (www.js96110.com.cn).
都不好解决，尝试打给国家反诈中心要求解封，电话 010-67825170。
苏州地区的解封在微信搜索：苏州市反通信网络诈骗中心，打开 封停申述-网站域名，填写申述表提交。
❗️ Pollution leads to walls
Because the domain name is contaminated, the content is not displayed in the original content. At this time, GFW detects that there is illegal content on your site, because the contaminated domain name does not jump, and the domain name is still your domain name, but the content changes. Therefore, GFW mistakenly believes that your domain name is an illegal site and pulls it into the blacklist. GFW will not listen to your explanation. This is caused by a consistent action.
这种情况域名建议直接抛弃了