At 10:16 PM, Saturday, April 4, 2009, TSO received an alert from our system monitoring solution that DNS services on one of the two secondary DNS servers in the college had failed. Shortly thereafter, DNS failed on the other secondary DNS server, as well. This affected DNS lookups for CoC faculty, staff, and students made during this time.
Subsequent investigation revealed that Domain Lookaside Validation (DLV) to dlv.isc.org was failing, causing all queries to domains outside those controlled by the college to fail.
TSO disabled DLV on the servers to allow proper DNS operation at 12:26 AM, April 5, 2009.
TSO's subscriptions to ISC mailing lists showed no planned outage of dlv.isc.org. TSO will continue to investigate the cause of the failed DLV, and will re-enable it when we can ensure continued operation of DNS.