[admin] Domain lookup issues fixed

Since Wednesday, there have been intermittent problems with lookup of the lambda-the-ultimate.org domain name. This was due to problems with our domain registrar, joker.com, which says it has been experiencing "massive distributed denial of service attacks" against its nameservers. Whether you experienced the problem depends on DNS caching and timing.

Although Joker continues to experience problems, we've now switched to domain name servers elsewhere, so the problem is resolved.