Radicenter nameservers are:

ns1.radicenter.com
ns2.radicenter.eu
ns3.radicenter.ee
ns4.radicenter.fi

Domaini parking in Radicenter is free of charge.

By free domain parking service we mean ability to register a domain through Radicenter and with our nameservers. The free domains parking service DOES NOT include the ability to manage domain DNS records. To manage DNS records, you must order a hosting service or to use other name servers.