We've enhanced how DNS trace tests work in the case of a SERVFAIL response received while looking up DNS records. Prior to this change, in the event that a SERVFAIL response were received by an agent, the test would fail with a "Dead End" error message. With the implementation of this change, upon receipt of a SERVFAIL response from an authoritative nameserver for a record, which has multiple authoritative nameservers, the next nameserver in the list will be tried, until either no remaining servers are available, or until the test timeout has been reached.