Fixing Firebase DNS on Namecheap: Remove the Domain From Host

If you're connecting Firebase to a domain on Namecheap (for custom email sending/verification), Firebase tells you which DNS records to add. The catch: Firebase shows fully‑qualified domain names (FQDNs) in the “Domain name” column, and Namecheap expects the Host field without your domain appended. If you paste the full name into Host, the record won’t resolve because Namecheap will duplicate your domain.

TL;DR: In Namecheap’s Host field, remove your domain suffix (like .teda.dev). Only enter the part before it.

The symptom

You add the records exactly as Firebase displays them.
Firebase can’t verify, or lookups show NXDOMAIN/no answer.
Namecheap support message: “domain names are automatically added by the system… manually adding them will cause duplication.”

Correct values for the Firebase example

Given Firebase shows these records for app.teda.dev:

TXT — Domain name: app.teda.dev — Value: v=spf1 include:_spf.firebasemail.com ~all
TXT — Domain name: app.teda.dev — Value: firebase=teda-fdd4c
CNAME — Domain name: firebase1._domainkey.app.teda.dev — Value: mail-app-teda-dev.dkim1._domainkey.firebasemail.com.
CNAME — Domain name: firebase2._domainkey.app.teda.dev — Value: mail-app-teda-dev.dkim2._domainkey.firebasemail.com.

Enter them in Namecheap like this:

# In Namecheap → Advanced DNS → Host Records

Type: TXT
Host: app
Value: v=spf1 include:_spf.firebasemail.com ~all

Type: TXT
Host: app
Value: firebase=teda-fdd4c

Type: CNAME
Host: firebase1._domainkey.app
Value: mail-app-teda-dev.dkim1._domainkey.firebasemail.com.

Type: CNAME
Host: firebase2._domainkey.app
Value: mail-app-teda-dev.dkim2._domainkey.firebasemail.com.

Notes:

Host removes the domain suffix (.teda.dev). Namecheap automatically appends your base domain.
The trailing dot on CNAME values is optional in Namecheap; it treats both with and without the dot the same.
If a record targets the root (apex) of your domain, set Host to @.

Why it happens

Firebase’s table uses fully‑qualified names to be unambiguous across registrars.
Namecheap’s UX assumes the zone you’re editing (e.g., teda.dev) and appends it automatically. Pasting the full name duplicates the domain, resulting in something like firebase1._domainkey.app.teda.dev.teda.dev.

Verification checklist

Wait up to 5–30 minutes (sometimes longer due to TTL and propagation).
From a terminal, run:

dig TXT app.teda.dev +short
dig CNAME firebase1._domainkey.app.teda.dev +short
dig CNAME firebase2._domainkey.app.teda.dev +short

You should see the TXT strings and the CNAME targets returned.

Namecheap UI steps

Log in → Domain List → Manage (for your domain).
Open Advanced DNS → Host Records.
Add new records or edit existing ones.
Put the shortened value in Host (no domain suffix), paste Firebase’s “Value” exactly, Save All Changes.

Rule of thumb for other providers

When a provider automatically appends your base domain, use only the left‑hand labels in the “Host” field. If the record appears as sub1.sub2.example.com in documentation, enter sub1.sub2 for Host.

That’s it—once the records resolve, Firebase verification and DKIM should pass.