DNS (Domain Name System) is the system that translates domain names into the servers behind them: it determines where your website loads and where email for your domain is delivered. The DNS records of your domain are therefore the road map of your digital presence.
DNS in practice
For businesses, three types of record matter most: MX records (where does mail come in), A/CNAME records (where the website runs) and TXT records for email authentication such as SPF, DKIM and DMARC. During a migration to Microsoft 365 or Google Workspace, switching over those records — the 'DNS cutover' — is the moment when the changeover actually takes place.
Make sure access to your DNS management (at your registrar) is in your own hands and documented: whoever can reach the DNS can redirect your mail and website. How a cutover proceeds without downtime is covered in the migration step-by-step plan.
Related terms
- SPF — SPF (Sender Policy Framework) is a DNS record that sets out which mail servers are allowed to send email on behalf of your domain.
- DKIM — DKIM (DomainKeys Identified Mail) adds a digital signature to every outgoing email that recipients can verify via DNS.
- DMARC — DMARC is the policy on top of SPF and DKIM: it tells receiving mail servers what to do with mail that does not pass the checks — simply deliver it (none), quarantine it or reject it (reject) — and sends reports on who is mailing on behalf of your domain.
- Tenant — A tenant is your own, cordoned-off environment within a cloud service such as Microsoft 365 or Google Workspace: all of your organisation's users, mailboxes, files, settings and security rules together.