@@ -3,6 +3,7 @@
 const {
   RegExp,
   RegExpPrototypeTest,
+  StringPrototypeIndexOf,
   Symbol,
 } = primordials;
 
@@ -46,6 +47,11 @@ function isIPv4(s) {
  * @returns {boolean}
  */
 function isIPv6(s) {
+  if (typeof s === 'string') {
+    // IPv6 always contains ':'. Skip the regex for IPv4 and hostnames.
+    if (s.length < 2 || StringPrototypeIndexOf(s, ':') === -1)
+      return false;
+  }
   // TODO(aduh95): Replace RegExpPrototypeTest with RegExpPrototypeExec when it
   // no longer creates a perf regression in the dns benchmark.
   // eslint-disable-next-line node-core/avoid-prototype-pollution