How to Create A Dynamic Dns and MX-record via freedns.afraid.org

Question

I'm in need of an mx record. I have comcast and they only allow you a few options for dynamic dns services, the free one being freedns.afraid.org. I've never set up an mx-record before so I obviously have little knowledge of what I'm dealing with. The options for both type "a" and "mx" are as follows:

Type:
Subdomain:  
Domain: crabdance.com   
Destination:

There is a dropdown selection of domains to choose from, I've chosen the crabdance.com domain.

For my 'A' record I have the following credentials.

Type: A
Subdomain:(myname)
Domain: crabdance.com
Destination: (public ip to my computer)

This results in (myname).crabdance.com

what would be a qualifying set of answers to fill out the mx record?

Type: A
Subdomain: [freedns.afraid.org says to leave this blank]
Domain: crabdance.com
Destination: ?

when I try to enter 10:mail.(myname).crabdance.com (this is recommended by freedns.afraid.org) I receive the following error messsage upon submitting the form:

Core subdomains (www, ftp, mail, irc, @) are reserved for the domain owner only [crabdance.com].

any help would be appreciated, thanks!

Answer 1

The set up for MX rewcord is as follows for freedns.afraid.org:

For A record:

Type: A
Subdomain:(myname)
Domain: crabdance.com
Destination: (public ip to my computer)

Now for the above A record, the MX record will look like:

Type: MX
Subdomain:(myname)
Domain: crabdance.com
Destination: 10:(myname).crabdance.com

Now any mail for say 'someone@(myname).crabdance.comwill be redirect to the server at(myname).crabdance.com`

Do watch at freedns.afraid.org site, when you click on Subdomain on left side, two records as follows:

(myname).crabdance.com  A   public IP address
(myname).crabdance.com  MX  10:(myname).crabdance.com

If you using LINUX, one can install inadyn in order to update the dynamic IP address at regular intervals, like:

sudo apt-get install inadyn

Once done, open inadyn.conf file like:

sudo vim /etc/inadyn.conf

and place these lines:

system [e-mail]
username yourusername
password yourpassword
update_period 60000
forced_update_period 320000
background
dyndns_system [e-mail]
syslog
alias (myname).crabdance.com

Now you can run inadyn like:

sudo inadyn

to update the IP address. That is it :-)

Here is the screenshot of freedns.afraid.org

Answer 2

I've not used this dynamic DNS service, but basically, they're telling you that the mail subdomain (probably even if you added a suffix like mail.yourlogin) is not permitted as they probably think you're trying to set a MX record for their own domain (crabdance.com).

In order to set the MX record, you should choose Type: MX where you have Type: A in your example. You indeed should fill in the subdomain with myname but without the mail keyword, and that should work.

In any case, if you still had problems, bear in mind that as per the RFC 5321 documentation regarding to DNS records, if there's not a MX record, the A record will be used by default and will be used as it were the MX server.