wiki.netbeans.org is a virtual host in netbeans-vm.apache.org
This URL was used in the pre-Apache days for hosting a MediaWiki wiki. This software is no longer installed by the ASF Infra Team (even thouth it's maintained, such as in https://wiki.openoffice.org/wiki/Main_Page).
The URL currently points to the wiki area of https://netbeans.apache.org/wiki, that contains a copy of the old "DevFAQ" NetBeans Developer FAQ.
This virtual host is configured using puppet with this YAML file https://github.com/apache/infrastructure-p6/blob/production/data/nodes/netbeans-vm1.apache.org.yaml
Let's Encrypt Certificates
Certificates will be automatically renewed. The NetBeans VM is one of the first Apache Projects to sport the mod_md module for handling SSL certificates.