A record maps a domain name to the IP address of the computer hosting that domain. For example, to access the Hexometer website you enter hexometer.com and there’s an A record that points to the particular IP address. This means all requests from the browser to hexometer.com are directed to the server with that IP address.
A Domain Name is an identification string that defines a realm of administrative autonomy, authority or control within the Internet. Domain names are used in various networking contexts and for application-specific naming and addressing purposes. In general, a domain name identifies a network domain, or it represents an Internet Protocol (IP) resource, such as a personal computer used to access the Internet, a server computer hosting a web site, or the web site itself or any other service communicated via the Internet.
To see domain name registration information simply check the whois data at https://hexometer.com/domain-whois
DNS is a hierarchical and decentralized naming system for computers, services, or other resources connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities.
MX record specifies the mail server responsible for accepting email messages on behalf of a domain name. It is a resource record in the Domain Name System (DNS). It is possible to configure several MX records, typically pointing to an array of mail servers for load balancing and redundancy.
TLD is one of the domains at the highest level in the hierarchical Domain Name System of the Internet. The TLDs are installed in the root zone of the name space. For all domains in lower levels, it is the last part of the domain name, that is, the last label of a fully qualified domain name. For example, in the domain name www.hxometer.com, the top-level domain is com. Responsibility for management of most top-level domains is delegated to specific organizations by the ICANN (Internet Corporation for Assigned Names and Numbers), which operates the IANA (Internet Assigned Numbers Authority), and is in charge of maintaining the DNS (Domain Name System) root zone.
ccTLD - country-code top-level domains
gTLD - generic top-level domains
.arpa - infrastructure top-level domain
Full list of TLDs is available at: https://en.wikipedia.org/wiki/List_of_Internet_top-level_domains