Index: modules/dns/dns.tcl
==================================================================
--- modules/dns/dns.tcl
+++ modules/dns/dns.tcl
@@ -791,11 +791,15 @@
         # using ceptcl
         set state(sock) [cep -type datagram $state(-nameserver) $state(-port)]
         fconfigure $state(sock) -blocking 0
     } else {
         # using tcludp
-        set state(sock) [udp_open]
+        if {[string match "*:*" $state(-nameserver)]} {
+            set state(sock) [udp_open ipv6]
+        } else {
+            set state(sock) [udp_open]
+        }
         udp_conf $state(sock) $state(-nameserver) $state(-port)
     }
     fconfigure $state(sock) -translation binary -buffering none
     set state(status) connect
     puts -nonewline $state(sock) $state(request)