Centosapache, can not resolve second-level domain names, beg for great solution

Centosapache cannot resolve second-level domain names. Suddenly, a domain name except the top-level domain name and a second-level domain name with www can be accessed. Other second-level domain names cannot be accessed. Resolution is successful and can be pinged. Enter the second-level domain name except www, the browser turns to half a day, and finally cannot open, this and the second-level domain name without domain name resolution and centos apache, can not resolve the second-level domain name, beg the gods
Yes. Suddenly, a domain name except the top-level domain name and a second-level domain name with www can be accessed. Other second-level domain names cannot be accessed. Resolution is successful and can be pinged. Enter the second-level domain name except www. the browser turns around for half a day and cannot open it at last. this is different from the second-level domain name without domain name resolution, because it does not do domain name resolution, as soon as you enter the Web site, it will be 404, and it will not take half a day.
It used to be normal. today it suddenly doesn't work. After a long time, it was still in the old state. It is absolutely impossible that the directory does not match.
The last thought was that Xinnet vps had blocked access to second-level domain names, but Xinnet had always had a bad attitude and directly denied it.
So I would like to ask you whether it is a configuration issue.
Thank you.
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Ping your second-level domain name to see if the bound ip address is your server ip address.
If there is no problem, check whether the second-level domain name and the directory to be accessed are correctly configured in IIS or apache httpd. conf on your server.
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Httpd. conf or nginx. conf.
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If the error url is entered, is it 404 or dns error?
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Restart
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Post your domain name