}
		}
		delete(checkHeader, formCanonicalName)
	}
	// For SignV2 - Signature/AWSAccessKeyId field will be ignored.
	if _, ok := formValues[xhttp.AmzSignatureV2]; ok {
		delete(checkHeader, xhttp.AmzSignatureV2)
		for k := range checkHeader {
			// case-insensitivity for AWSAccessKeyId
			if strings.EqualFold(k, xhttp.AmzAccessKeyID) {
				delete(checkHeader, k)
				break
			}
		}
	}

		if h.Truncated && network == "udp" {
			continue
		}
		return p, h, nil
	}
	return dnsmessage.Parser{}, dnsmessage.Header{}, errNoAnswerFromDNSServer
}

// checkHeader performs basic sanity checks on the header.
func checkHeader(p *dnsmessage.Parser, h dnsmessage.Header) error {
	rcode, hasAdd := extractExtendedRCode(*p, h)

	if rcode == dnsmessage.RCodeNameError {
		return errNoSuchHost
	}