src/pkg/net/dnsconfig.go | 6 +++++-

diff --git a/src/pkg/net/dnsconfig.go b/src/pkg/net/dnsconfig.go
index 7d098583df262763d7d65ba6b583ddaa51a980c9..4be207603cf20d583c66b974691f4409398f3fa4 100644
--- a/src/pkg/net/dnsconfig.go
+++ b/src/pkg/net/dnsconfig.go
@@ -49,7 +49,11 @@ 				// One more check: make sure server name is
 				// just an IP address.  Otherwise we need DNS
 				// to look it up.
 				name := f[1]
-				if len(ParseIP(name)) != 0 {
+				switch len(ParseIP(name)) {
+				case 16:
+					name = "[" + name + "]"
+					fallthrough
+				case 4:
 					a = a[0 : n+1]
 					a[n] = name
 					conf.servers = a