Is there a root DMARC record?

Yes. Nice work!

You have a root DMARC record with this value:

  
      "v=DMARC1; p=reject; sp=reject; pct=100;fo=1; ri=3600;  rua=mailto:dmarc.rua@samplecorp.com; ruf=mailto:dmarc.ruf@samplecorp.com"
    

Digest your DMARC records →

Why is this important?

By having a root DMARC record, all emails sent from samplecorp.com, including any subdomains of samplecorp.com that don't have a specific DMARC policy, will have this "catch-all" policy applied to them.