Shulou(Shulou.com)05/31 Report--

In this issue, the editor will bring you about how to solve the problem of Let's Encrypt SSL certificate "DNS problem: NXDOMAIN looking up A for xxx.com". The article is rich in content and analyzes and narrates it from a professional point of view. I hope you can get something after reading this article.

Resolve Let's Encrypt SSL certificate configuration error "DNS problem: NXDOMAIN looking up A for xxx.com"

With the increasing utilization of HTTPS, the demand for SSL certificates is also increasing. As of September last year, 10 million certificates had been issued by the world's largest free Let's Encrypt certificate. In the past, the installation of SSL certificates required certain technical requirements, so it is cumbersome and difficult for some users to install and configure according to the official steps.

However, now everything has become simple and fast, after many promotions and changes by developers, Let's Encrypt certificates to achieve one-click installation. After the domain name in which the Let's Encrypt certificate is installed is resolved to the current server and takes effect, it can be installed when the site is added. However, this convenient installation will also encounter some error prompts, and some users will see an error message "DNS problem: NXDOMAIN looking up A for xxx.com" during the wizard to install the Let's Encrypt certificate. How to solve this kind of error prompt?

1. Problem: Let's Encrypt configure SSL certificate

Use Let's Encrypt to configure SSL certificate error reporting:

DNS problem: NXDOMAIN looking up A for xxx.com

Second, the reason

The reason for this problem may be:

The A record has just been parsed, and the resolution server has not yet taken effect.

The server local DNS cache has not been updated

Third, solve the problem

Determine whether the A record is effective

Before adding a domain name, you need to resolve the domain name A record to the server IP address, and you need to wait for it to take effect before automatic verification. If the parsing is not successful, the above error will occur.

If it is detected by the PING tool that both WWW without the current domain name and WWW are resolved to the server, execute the second case.

Determine if there is a problem with DNS

1) ping host

# ping host. If host cannot be found, it is determined to be a dns problem.

$ping demo.ptbird.cn

2) Update DNS cache

Direct network restart is not recommended

Use nscd

If the system is not installed, you can install it. Nscd is very useful for DNS cache acceleration.

Centos: yum install nscd

Ubuntu: apt-get install nscd

If a direct update has been installed

# mainly hosts

$nscd-I passwd

$nscd-I group

$nscd-I hosts

3. Add a WWW site

If it is neither of the above, it is the problem with WWW. When you can add a site directly, you can only add the WWW domain name, and you can install the Let's Encrypt certificate, and then after the installation, you can manually add the domain name without WWW by modifying the conf configuration file, and the problem is solved by setting 301 to force the jump.

The above is the editor for you to share how to solve the Let's Encrypt SSL certificate "DNS problem: NXDOMAIN looking up A for xxx.com" problem, if you happen to have similar doubts, you might as well refer to the above analysis to understand. If you want to know more about it, you are welcome to follow the industry information channel.

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