docker unable to access website

After came to my girlfriend’s home, I find my docker unable to access website.
I could not ping by domain name, I thought it is the problem of my gf’s router.
Any ping could only return unknown host XXXXXX, this seems not the problem of network connection but something else.

Today I find the problem is in domain name resolution. A similar issue on github.
Accroding to this page, I modified /etc/resolv.conf as my host machine’s, then DNS problem solved.

The reason of this problem is that, I created this docker container in my home, which has different DNS from my gf home’s. But docker container unable to detect the change after I came here.

Thanks to lz, his idea of examing DNS reminds me.