I run a DNS monitoring service and have had a number of customers contact me about this in the past couple hours. Most of them were using Route53, but this is an issue with the IO authoritative nameservers, rather than Route53 itself.
I created DNS Check because I wanted to be able to easily import all my DNS records (not just the A and AAAA records) into a tool that would automatically monitor them, and notify me if they change. I couldn't find any existing tools that do that, so I created one.
If you have any questions, or suggestions for how to improve this tool, I'd love to know.
1. Pick some subset of your DNS records to monitor, or all of them if you want to be extra thorough. If you are picking a subset, then I'd pick whatever records are most critical to your business.
2. Setup monitoring that queries each of your authoritative name servers for each of the records that you identified in the previous step. The monitoring should notify you if any of the name servers are unresponsive, or return a different response than what's expected.
If you'd like to dig into the details of DNS, then O'Reilly's "DNS and BIND" is highly recommended, even if you're not using BIND.
There are a number of quality hosting providers out there. A rule of thumb that I use is this: If a DNS hosting provider doesn't eat their own dog food, don't trust them to handle your DNS. Digital Ocean doesn't use their own name servers for their main website's domain. Neither does Amazon.
Shameless plug: I created a DNS monitoring service that can be used used for monitoring each of your name servers: https://www.dnscheck.co/
Are you sure that's still the case? I recently switched one of my site's transactional mail from a free Mandrill account to a free SendGrid account, and have not seen this issue.
I'm assuming that the issue you're referring to is triggered by the presence of a Sender header. The Sender header is present in the emails that SendGrid sends for the site in question.
The Return-Path and From address are at the domains that I specified (e.dnscheck.co and dnscheck.co).
Perhaps this is something that has recently changed, or is only an issue with certain configurations.
Thanks for the feedback, Sephr. I'm new to posting on HN, and want to make sure I don't repeat any mistakes that were made when sharing this article.
I am the author of the article, and certainly don't want to obscure that. I'm gathering from your feedback that submitting this article to HN with a title of "How I Check My MX Records" would be more appropriate. Is that correct?
The article discusses MX record concepts, and potential problems, followed by three methods for checking MX records. Using the dig and nslookup commands are the first two methods, and the DNS Check service is the third. My intent is for the article to be be useful for someone using any of those options. Is sharing that type of article discouraged on HN?