code: func (p preCheck) checkDNSPropagation(fqdn, value string) (bool, error) {
  	// Initial attempt to resolve at the recursive NS
  	r, err := dnsQuery(fqdn, dns.TypeTXT, recursiveNameservers, true)
  	if err != nil {
  		return false, err
  	}
  
  	if !p.requireCompletePropagation {
  		return true, nil
  	}
  
  	if r.Rcode == dns.RcodeSuccess {
  		fqdn = updateDomainWithCName(r, fqdn)
  	}
  
  	authoritativeNss, err := lookupNameservers(fqdn)
  	if err != nil {
  		return false, err
  	}
  
  	return checkAuthoritativeNss(fqdn, value, authoritativeNss)
  }
docs: // checkDNSPropagation checks if the expected TXT record has been propagated to all authoritative nameservers.