code: func (va ValidationAuthorityImpl) getAddrs(ctx context.Context, hostname string) ([]net.IP, *probs.ProblemDetails) {
  	addrs, err := va.dnsClient.LookupHost(ctx, hostname)
  	if err != nil {
  		problem := probs.DNS("%v", err)
  		return nil, problem
  	}
  
  	if len(addrs) == 0 {
  		return nil, probs.UnknownHost("No valid IP addresses found for %s", hostname)
  	}
  	va.log.Debugf("Resolved addresses for %s: %s", hostname, addrs)
  	return addrs, nil
  }
docs: // getAddr will query for all A/AAAA records associated with hostname and return
  // the preferred address, the first net.IP in the addrs slice, and all addresses
  // resolved. This is the same choice made by the Go internal resolution library
  // used by net/http.