Can I use a CNAME record at the zone apex (root domain)?

No. RFC 1034 forbids CNAME at the zone apex because it conflicts with SOA and NS records. Use an A record or your provider's ALIAS/ANAME flattening feature instead.

Does a CNAME record affect website performance?

Slightly. A CNAME adds one extra DNS resolution step (the alias lookup + the target lookup). For most sites the difference is negligible, but CDN providers often use CNAME for edge routing.

Can I point a CNAME to an IP address?

No. A CNAME must point to another domain name, never to an IP address. Use an A record (IPv4) or AAAA record (IPv6) to point directly to an IP.

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CNAME vs A Record — When to Use Which

CNAME vs A record: what each does, when to use which, and the apex domain rule that breaks naive setups. Free instant DNS lookup, no sign-up.

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Problem

You need to add a DNS record but aren’t sure whether to use a CNAME or an A record.

Key Differences

Feature	A Record	CNAME Record
Points to	IP address (e.g., `93.184.216.34`)	Another domain (e.g., `cdn.example.net`)
Zone apex	Allowed	Not allowed (RFC 1034)
Extra lookup	No	Yes (one additional resolution)
Use case	Root domain, direct IP mapping	Subdomains, CDN, cloud services

Top 3 Decision Rules

Root domain (example.com) → Always use an A (or AAAA) record. CNAME is not valid at the zone apex.
Subdomain pointing to a cloud service (e.g., app.example.com → myapp.herokuapp.com) → Use CNAME so the target IP can change without updating your DNS.
Subdomain with a known, static IP → A record is simpler and avoids the extra lookup.

Diagnosis with DechoNet

DNS Lookup — Query your domain and check the Records tab to see which record types are configured.
Verify CNAME targets resolve correctly by looking up the target domain.

Resolution Checklist

Use A/AAAA for the root domain (example.com).
Use CNAME for subdomains that point to external services (CDN, PaaS, SaaS).
Never mix CNAME with other record types on the same name (MX, TXT, etc.).
If your DNS provider supports ALIAS/ANAME, you can use it as a CNAME-like record at the apex.
After changes, verify with DechoNet DNS Lookup that records resolve as expected.