Required DNS records
DNS, which stands for domain name system, controls your domain name's website and email settings. When internet users visit your domain name, the DNS settings control which company's server it reaches out to.
A Records (Address record) map your domain name to an individual server using an IP address. Two A records required.
mail.domainname.st. with TTL 14400 and that will point to domain IP address in RDATA
domainname.st same TTL and IRDATA
CNAME (Canonical name) maps your subdomains to another server using a server name. Unlike A Records, CNAMEs cannot use IP addresses. Most domain names have many CNAMEs.You can set several CNAMES if neede.
Basic one is
www.domainname.st same TTL and domainname.st as RDATA
MX Records (Mail Transfer record) references the server that handles email for your domain.
domainname.st same TTL, RDATA include integer number, that is used to prioritize mail delivery if multiple mail servers are available, and mail.domainname.st
Nameservers (Authoritative Name Server Record) maps your domain name to the company that controls its DNS settings.
On nic.st you are allowed to use 1 - 5 nmeservers.