By Nicolas Avila · October 9, 2026

DNS: what breaks when someone changes it incorrectly

Photo: Avila Ops Tecnologia

An incorrect DNS record breaks one thing at a time, and what breaks tells you which record it was: a website outage points to the address record (A or CNAME); email that stops arriving points to the mail record (MX); email going to spam points to authentication records (SPF, DKIM, DMARC); everything going down at once points to changed name servers (NS). Knowing this turns a day of panic into a 15-minute check.

The address list DNS represents is explained in the basic guide: What is DNS, without technical jargon?. Problems start when someone edits that list without knowing what each line does.

What are the five most common mistakes?

These are the cases Avila Ops gets called to solve.

1. Deleting the MX record when changing hosting. The new provider sets up the website and “cleans up” DNS. The website goes live; email stops. No one notices until a customer says an email bounced.
2. Pointing the website to the new server before it exists there. DNS changes, and visitors reach a blank page or the host’s default screen. The correct order: prepare the website on the new server, then change DNS.
3. Changing all name servers (NS) to the new provider without copying old records. Every destination disappears at once: website, email, store, subdomains, Google verification.
4. Duplicating a record with the same name. Two A records for the same address, one pointing to the old server and one to the new. The website opens for some people and fails for others.
5. Forgetting email authentication records (SPF, DKIM) when changing email services. Email sends but lands in spam or is rejected. When it lands in spam, no one tells the sender.

What does each mistake break, and how do you recognize it?

Each record type is defined in the glossary: avilaops.com/glossario/dns.

How do you change DNS without breaking anything?

Export or photograph the current list. It is the only way to roll back if something goes wrong. Without a copy, the old list disappears with the first save.

Change one record at a time and test. Changed the website record? Check the website. Changed MX? Send a test email from an external account. Never change five lines at once.

Never change name servers (NS) before recreating all records at the destination. NS is the address of the list itself; changing it without copying is throwing the list away.

Reduce the record’s time to live (TTL) one day before the change. This makes the internet check the list more often and makes the switch take effect faster. Restore the normal value afterward.

Make changes during low-traffic hours with someone monitoring. And if your website provider asks for DNS access to “just point it,” first ask for a list of what they will change.

What to do now

Export your domain’s DNS list today and store it somewhere you control. If someone will edit it this month, request the change list in writing and check it against the table above. A domain in your name, automatic renewal, no surprises: avilaops.com/dominio-e-hospedagem or contact us on WhatsApp: wa.me/5517997811471.

Frequently asked questions

I changed DNS and the website went down. What should I do?

Compare the current list with the previous one. If the website record (A or CNAME) points somewhere the website does not exist, restore the old value. Without the previous list, ask your old host for the correct address. Reverting can also take up to 48 hours to take effect everywhere.

Why did my email stop working after I changed the website?

Almost always because the MX record was deleted or changed along with website records. Recreate MX using the values your email service provides, and check SPF and DKIM records. Messages sent during the gap may have bounced to their senders.

How long does DNS take to propagate?

From minutes to 48 hours, depending on the time to live (TTL) set before the change. Reducing TTL one day beforehand speeds the switch. If more than 48 hours have passed and it still does not work, the problem is the record, not propagation.