What are CNAME and A DNS records? What are they used for? What is the difference between the two?
Edit: Where does the CNAME record exist? On the server or with the domain registrar?
A cname record is a pointer that points to a fully qualified domain name(fqdn), an A Record is a pointer that points to an ip adress.
Edit: these records exist on your aptly named Name Server (aka NS) which your registrar points to.
Edit #2: A CNAME record would in some cases is preferred to a a record where you can't actually point to an IP address because it changes. One example of this would be a cloud service where the server IP address changed and the service doesn't manage your name records you have to use a CNAME to point to an address that they can dynamically update. Another one would be the DDNS services, most of the modern dsl modems support this feature, when enabled at your modem every time the ip address changes your modem updates the service and you have one up-to-date fqdn which later you can point to.
A record: Returns a 32-bit IPv4 address, most commonly used to map hostnames to an IP address of the host, but also used for DNSBLs, storing subnet masks in RFC 1101, etc.