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Is mx record means
once anyone want to send the mail to others, they have to go to dns to register a one mx record , that is a domain name, such as hotmail .com, in this domain name will point to at least one address of the server.
So , it introduce reverse dns, which is , when I send the mail to the others, the other side will check whether the ‘from’ ip has a domain name in public dns , if the ip can not find any domain name related to it, the mail server will block the incoming message.
Is my concept correct? And what is A record and PTR do ?
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If I send an e-mail to yourdomain.com, it checks for the MX-records of yourdomain.com to find which mailserver(s) handles this.
Your second paragraph is correct. Many enables the option to check the reverse lookup of the IP sending the e-mail.
Your concept is correct indeed!
A-record is a record pointing to the IP-address of a server.
A typical record could look like:
yourdomain.com 521 IN A 192.168.1.1 (<- random IP)
When you run a ping against yourdomain.com it will try the IP listed in the A-record.
PTR records are reverse lookup records.
I hope any of this makes sense!
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