DNS Abbreviations

CA: Certification Authority
CAA: Certification Authority Authorization
CSR: Certificate Signing Request
DNS: Domain Name System
FQDN: Fully Qualified Domain Name
RR: Resource Record (in DNS)
SSL: Secure Sockets Layer

IPv4

IPv4 is the fourth version of the Internet Protocol. The first widely used version of the Internet Protocol, it forms an important technical basis for the internet and data transmission in networks.
This 32-bit protocol enables devices to communicate online and on local networks. It also allows data packets to be routed to their intended destination.

IPv6

IPv6 is the latest version of the Internet Protocol and therefore the current standard for identifying devices on the Internet and in local networks.
It was developed to overcome the limited address space of its predecessor, IPv4, and to better meet modern internet requirements.
A key feature of IPv6 is its 128-bit address length, as opposed to IPv4's 32-bit length. This longer address length enables an almost unlimited number of unique IP addresses.

Subdomain

A subdomain is a sub-section of a parent domain. It is used to organize and structure different sections or services within a main domain.
For the domain www.rwth-aachen.de, idm.rwth-aachen.de and online.rwth-aachen.de are subdomains.

Zone

A DNS zone is a specific area within the Domain Name System (DNS) that serves to distinguish between different, separately managed areas in the DNS namespace and to enable control over the DNS components.
A DNS zone can contain one or more subdomains, allowing an entity to have multiple subdomains under its administration.