前两天，在测试服务器上通过配置host来测试系统，发现在IE下面cookie的读写存在问题，一开始以为是代码和框架的问题，于是写了一个最简单的PHP页面来读写，发现依然不行。通过fiddler抓包软件发现cookie确实有正常的传输，说明网络是OK的。后来怀疑是php配置的问题，于是将PHP语言转换为JS来读写COOKIE，发现依然不行。后来无意中一个测试的同事通过域名直接访问，在IE下的cookie读写正常，于是怀疑是域名中有特殊的字符因为了IE对cookie解析的异常。经过排查，发现域名中带有“_”的域名都会引起IE cookie异常。将_去掉，一切正常。最后通过查找资料发现如下的信息：

According to RFC1035 (Domain names - implementation and specification):
[domain names] must start with a letter, end with a letter or digit, and have as interior characters only letters, digits, and hyphen.
Turns out some of the domains had an underscore ( "_" ) in them: some_domain.example.com. Although this is a violation of the RFC, all other browsers work normally.
MSIE 7, on a domain with an underscore, silently drops all cookies for that host and refuses to accept new ones.
The only solution is to use RFC-compliant domains (I‘ve replaced all the "_"s with "-"s and set up a RewriteRule so that traffic is redirected to the compliant domains).

根据RFC1035规则，域名的实现和规范必须以字母开头，以字母或者数字结束，其他的部分必须数字，字母或者连字符-。

同时提到msie7，域名中包括_，将会丢弃掉所有的cookie并拒绝接受新的。