TLD Survey:Closed to TCP Queries?

• Methodology

  • For each server/ip pair, as quickly as you can, do:

    • UDP-only query

      • dig @server zone. any +novc
    • TCP-only query

      • dig @server zone. any +vc
    • UDP-only query

      • dig @server zone. any +novc
    • Repeat sequence 35 times
  • If, for all 35 queries, queries #1 and #3 were successful and query #2 timed out, then we conclude that they are probably closed

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