Conceptual Overview of Earning the Professional-Level Certification
Your task at this level is to ensure your mail server has reverse DNS records (rDNS) or pointer (PTR) records that work over IPv6.
- Add a reverse zone on dns.he.net using the /64 Routed IPv6 Prefix
- Create an PTR record, which is the Client IPv6 Address and the forward DNS FQDN
- Ask HE to check for the records
Why Do We Need A Reverse Record?
Regular DNS (forward) contains records of the IP address at which a domain is located. So jacobsalmela.com may be at IP address 22.214.171.124. However, reverse DNS is also necessary because IP address 126.96.36.199 may not necessarily point to jacobsalmela.com.
These records are also important because we set up a mail server. Many e-mail servers on the Internet are configured to reject incoming e-mails from any IP address which does not have reverse DNS.
Just like we have AAAA records to indicated IPv6, and MX records to indicate a mail server, PTR records indicate a reverse lookup.
Create A Reverse Zone Record
1. Log into dns.he.net
2. Click Create new reverse
3. Paste in the /64 Routed IPv6 Prefix from the Tunnelbroker site
4. Click Create
Create A PTR Record
1. Click Additional > New PTR
2. Enter your FQDN into the fields
3. Click Submit
Have HE Check The Records
- Navigate to ipv6.he.net
- Click the link on the bottom to have them check your PTR records