diff --git a/resolver/dns/dns_resolver.go b/resolver/dns/dns_resolver.go
index <HASH>..<HASH> 100644
--- a/resolver/dns/dns_resolver.go
+++ b/resolver/dns/dns_resolver.go
@@ -66,6 +66,9 @@ type dnsBuilder struct {
 
 // Build creates and starts a DNS resolver that watches the name resolution of the target.
 func (b *dnsBuilder) Build(target resolver.Target, cc resolver.ClientConn, opts resolver.BuildOption) (resolver.Resolver, error) {
+	if target.Authority != "" {
+		return nil, fmt.Errorf("Default DNS resolver does not support custom DNS server")
+	}
 	host, port, err := parseTarget(target.Endpoint)
 	if err != nil {
 		return nil, err
DNS resolver: Throw an error for non-default DNS authority. (#<I>)