Explanation/Reference: https://httpd.apache.org/docs/2.4/ssl/ssl_faq.html#aboutcerts

Explanation
DANE stands for DNS-based Authentication of Named Entities. It is a protocol that provides a way to verify the association of X 509 certificates to DNS host names. X 509 certificates are digital documents that contain the public key and identity information of an entity, such as a web server or an email server. They are used to establish secure connections and authenticate the identity of the entity. However, the traditional way of obtaining and validating X 509 certificates relies on a hierarchical system of trusted third parties, called certificate authorities (CAs), which can be vulnerable to attacks or compromise. DANE aims to enhance the security and trust of X 509 certificates by using DNSSEC, which is a set of extensions to DNS that provide cryptographic signatures and validation for DNS records. DANE allows the owner of a domain name to publish the X 509 certificate or its fingerprint in a DNS record, called a TLSA record, which can be verified by the DNSSEC chain of trust. This way, the client can check the authenticity of the certificate directly from the DNS, without relying on external CAs. DANE can also be used to specify which CAs are authorized to issue certificates for a domain name, or to indicate that no CA is needed at all. DANE can be applied to various protocols that use X 509 certificates, such as HTTPS, SMTP, IMAP, POP3, etc.
References:
DANE - Wikipedia
DNS-Based Authentication of Named Entities (DANE) - Internet Society
DANE: Taking TLS Authentication to the Next Level Using DNSSEC

AllowUsers
Explanation:
The option in the sshd configuration file that instructs sshd to permit only specific user names to log in to a system is AllowUsers.
This option can be followed by a list of user name patterns, separated by spaces, that are allowed to log in.
For example:
AllowUsers alice bob
This will allow only alice and bob to log in via ssh. Any other user will be denied access. The AllowUsers option can also take the form USER@HOST to restrict logins to particular users from particular hosts. For example:
AllowUsers [email protected].* [email protected]
This will allow alice to log in from any host in the 192.168.1.0/24 network, and bob to log in from the host example.com. The AllowUsers option can be used in conjunction with the DenyUsers option, which does the opposite. The allow/deny directives are processed in the following order: DenyUsers, AllowUsers, DenyGroups, and finally AllowGroups.
References:
sshd_config - OpenSSH SSH daemon configuration file
Allow Or Deny SSH Access To A Particular User Or Group In Linux - OSTechNix