diff --git a/data/dns/ck.dn42 b/data/dns/ck.dn42
index acafd5418..fef934ddb 100644
--- a/data/dns/ck.dn42
+++ b/data/dns/ck.dn42
@@ -3,7 +3,7 @@ descr:              CK network Service
 admin-c:            CK-DN42
 tech-c:             CK-DN42
 mnt-by:             CK-MNT
-nserver:            ns1.ck.dn42
-nserver:            ns2.ck.dn42
-nserver:            ns3.ck.dn42
+nserver:            ns1.ck.dn42 172.20.231.21
+nserver:            ns2.ck.dn42 172.20.231.22
+nserver:            ns3.ck.dn42 172.20.231.23
 source:             DN42