DNS is the system used to control where your domain name points to. It controls what service handles your emails, what server to route web traffic to, how subdomains should be handled, and much more.
Why check DNS changes?
If there are changes to your DNS entries it can mean a number of things. Often it's a perfectly legitimate change - perhaps you're moving server, adding an email server to your network, or adding a validation record for something. Sometimes though, DNS changes can be brought about by faulty name servers, human error or even malicious attacks.
How do we check DNS changes?
Janitor runs a DNS check against your root domain name using your name servers. Effectively, we ask your name servers for all of the DNS records attached to the domain name. What your name server actually gives us may differ depending on how it is configured, but usually we'll get a list of A records, a list of MX records, CNAME records and some TXT records.
A records are the easiest to understand, and work as a pointer to an IP address/server.
MX records are used for routing email.
CNAME records are aliases for other records.
TXT records contain some text, usually used for verifying ownership of a domain with various services.
Janitor checks these records and and saves them in our database. The next time the check runs we'll check the previous records for differences.
What happens if my DNS changes?
Don't panic. Check your services to ensure everything is operating properly.
Within the Janitor dashboard you'll be able to find the log from the check. The log entry (which will have been sent to you on Slack and email) will contain details of your DNS entries before and after the most recent check. You can go back as far as you want to view previous checks since the start of your account, just in case things have changed multiple times.
If something has changed that shouldn't have you should have all the information you need to change things back.