The SlickDNS domain editor page divides DNS records into three groups:
Host address records are the most common and most important type of DNS records as they map host names to IP addresses. You can only read this page because we have configured the www host record for the domain slickdns.com to point to the SlickDNS web server’s IP address!
A records map host names to IP (i.e., IPv4) addresses and AAAA records map host names to newfangled IPv6 addresses. The SlickDNS editor is smart enough to figure out which is which based on the syntax of the IP address entered.
Note: Before you create any address records for your domains, we strongly recommend that you read the article on configuring servers.
CNAME (“Canonical Name”) records basically specify that one domain name is an alias for another name and that the IP address of the pointed to “canonical” name should be also be used for the alias name.
Here’s a typical example of where you’d use a CNAME record: Suppose you own the domain example.com and want to add a blog to the example.com website, and want the URL for the blog to be http://blog.example.com. However, rather than host your own blogging platform you’d prefer to use a third-party blogging platform such as Blogger or Tumblr. With a CNAME record you can create the blog on the third party service where the domain name for your blog will be something like exampleblog.blogspot.com and you can set it as the canonical name for blog.example.com. So your blog appears to be hosted on your server but the blog pages are actually served from Blogger’s blogspot.com servers. (E.g., see this page for the Blogger instructions for creating CNAME records for custom domains.)
Strictly speaking there is no “HTTP” record type, but for convenience the SlickDNS record editor includes the ability to map names to HTTP URLs. (Under the hood they’re implemented by creating A records that point to the SlickDNS redirect servers which then do a HTTP redirect to the destination URL.)
MX records list the mail servers responsible for receiving email for the domain. (MX stands for “Mail eXchange”, not to be confused with Microsoft’s Exchange mail server product!)
MX records specify the email server host name and a preference number used to indicate the relative priority if multiple mail servers are listed. Note that the lower the preference number is, the higher the priority of the mail server.
See this Wikipedia article for more information about MX records.
This last section is a grab bag of miscellaneous record types that are usually only needed for advanced DNS configurations.
Nowadays TXT DNS records are most commonly used to create so-called SPF and DKIM records to authenticate email servers. If you use a third-party service like Campaign Monitor or Postmark to send emails on behalf of one of your domains, you’ll almost certainly need to create TXT SPF and/or DKIM records to verify that their email servers are authorized to send emails on your behalf.
Note that SlickDNS automatically generates NS and SOA (“Start of Authority”) records for any configured domains. The only time you need to manually create NS records is if you want to delegate subdomains to third-party name servers.
SRV records are a pretty obscure record type that are most commonly created for SIP VoIP servers. See the Wikipedia page for more details.