问题描述：版本升级后未做出厂设置时，无法查询成功（gethostbyname无法获取到正确结果）。
问题原因：
gethostbyname这个DNS解析器系统调用，其查询的信息来自于系统DNS解析缓存（ 库函数只读一次存储dns的文件，放到缓存里），当之前存在过错误的解析或者说解析错误时，系统DNS解析缓存不会被更新，因此之后再调用就会一直失败。
因此当DNS SERVER信息更新后，gethostbyname就会解析不出地址了。
解决方法：更新解析缓存，当出现gethostbyname调用失败时使用res_init()函数来更新DNS缓存，然后再调用gethostbyname。
解决结果：成功解决。
示例代码：
Hey there 🙂
Your wordpress site is very sleek – hope you don’t mind me asking what theme you’re using?
(and don’t mind if I steal it? :P)
I just launched my site –also built in wordpress like yours– but the theme slows (!) the site down quite a bit.
In case you have a minute, you can find it by searching for “royal cbd” on Google (would appreciate any feedback) –
it’s still in the works.
Keep up the good work– and hope you all take care of yourself during
the coronavirus scare!
Hi Justin,
Sorry for late reply. The theme is ‘Amadeus ：Version 2.0.7″.
Long time reader, first time commenter — so, thought I’d drop a comment..
— and at the same time ask for a favor.
Your wordpress site is very simplistic – hope you don’t mind me asking what theme
you’re using? (and don’t mind if I steal it? :P)
I just launched my small businesses site –also built in wordpress like yours– but the theme slows
(!) the site down quite a bit.
In case you have a minute, you can find it by searching for “royal cbd” on Google (would
appreciate any feedback)
Keep up the good work– and take care of yourself during the coronavirus scare!
~Justin
Great content! Super high-quality! Keep it up! 🙂
Awesome post! Keep up the great work! 🙂