code: func LookupCNAME(host string, server string, c *dns.Client, m *dns.Msg) (addrs []string, err error) {
  	m.SetQuestion(dns.Fqdn(host), dns.TypeCNAME)
  	r, _, err := c.Exchange(m, net.JoinHostPort(server, "53"))
  	if err != nil {
  		return nil, err
  	}
  
  	for _, ans := range r.Answer {
  		if t, ok := ans.(*dns.CNAME); ok {
  			addrs = append(addrs, t.Target)
  		}
  	}
  
  	return
  }
docs: // CNAME record lookup