As noticed by some in the Internet network operations community, at the beginning of May an odd event occurred as ICANN ended DNS service on the IP address formerly associated with L.ROOT-SERVERS.NET (”L-root”). Specifically, as ICANN turned off the DNS service at the address formerly used by the L-root, 198.32.64.12 (and the routing announcement by ICANN for 198.32.64.0/24), DNS root queries sent to that address instead of the new L-root address (199.7.83.42) continued to be answered.

At ICANN and for those who were aware of the situation this raised some eyebrows. Immediately after we turned off the old DNS server and noticed queries for the old address kept getting answers, we began looking into the issue by checking the DNS responses, reviewing routing system logs (including asking folks at Renesys and others for assistance), doing traceroutes from various points in the Internet, etc. Our investigation determined that the answers being provided by the machines now answering for the old L-root address were correct, returning proper referrals and answers including returning the correct address (199.7.83.42) for L-root, and as such, no immediate damage was being done. However, those answers should not have been returned period.

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