What is a “lame” delegation?
From Bryan Beecher A lame delegation is an instance when a nameserver has been listed as authoritative for a domain, but does not seem to be performing authoritative service for that domain. That is, the nameserver appears to be answering out of its cache instead of out of its data. Note that even a server which is performing secondary service for a domain is still an authoritative server, and should be returning authoritative data.