There are different types of DNS entries depending on the type of use:
A-Records
A records stand for a host entry, e.g., www. and refer to an IP address of a server e.g. Web server.
Example: The domain yourdomain.com has an A-record that points to the IP address 77.244.243.2.
AAAA
AAAA stands for the same type of entry as for the "normal" "A" record, but this entry is intended to use IPv6 addresses. When using IPv6, this entry has priority over the normal "A" entry.
Example: The domain yourdomain.com has an AAAA record pointing to the IPv6 address f3b0:1:cb3a:b4b0:7872:5ef9:93bb:e7a2.
ALIAS / ANAME Records
ALIAS / ANAME Records have the same purpose as CNAME Records, but are technically different. It is about assigning an IP to the domain via a host name. They allow e.g., refer the root record in the domain to a destination host name.
Example: The domain yourdomain.com has an ALIAS record pointing to the hostname www.yourdomain.com.
CNAME
This DNS entry is used if the hostname should be referenced instead of an IP address. CNAME entries, unlike ALIAS / ANAME entries, can only be used with subdomains.
Example: The subdomain test.yourdomain.com has a CNAME record pointing to the hostname www.yourdomain.com.
MX Record
MX Records are responsible for specifying a domain one or more mail servers with priority (10, 20, 30, etc.). The lowest value is the first mail server to use.
Example: For the domain yourdomain.com there is an MX entry pointing to the easyname mail server mx01.easyname.eu.
NS records
NS records are used to set a name server for a single domain
Example: For the domain yourdomain.com an NS entry is set which points to the easyname name server ns1.easyname.eu.
SRV records
SRV records allow the definition of the availability of IP-based services offered under a domain and are required for the use of certain services and applications such as SIP / VoIP or XMPP (Office 365, Jabber, Instant Messaging, etc). You can also specify the port and the protocol via an SRV entry.
Example: For _sip._tls.yourdomain.com an SRV entry is set to use the SIP service with the TLS protocol. This entry points to the hostname 443 sipdir.online.lync.com.
TXT records
TXT records contain freely selectable text. On some systems, the content is used to encode administrative data. TXT records are also used to create an SPF entry .
Example: For the domain yourdomain.com there is a TXT entry with the following content: "v = spf1 include: spf.easyname.com -all"