We got some very weird compaints about applications "hanging." Tracked it down to reverse lookups timing out. Reverse lookups to RFC1918 space. Looks like the IANA blackhole servers for RFC1918 are not well? 1 0.00000 207.88.152.10 -> 192.175.48.6 DNS C 52.143.18.172.in-addr.arpa. Internet PTR ? 2 0.01375 192.175.48.6 -> 207.88.152.10 ICMP Destination unreachable (UDP port 53 unreachable) 3 0.68455 207.88.152.10 -> 192.175.48.6 DNS C 111.143.18.172.in-addr.arpa. Internet PTR ? 4 0.00529 192.175.48.6 -> 207.88.152.10 ICMP Destination unreachable (UDP port 53 unreachable) 5 3.00417 207.88.152.10 -> 192.175.48.42 DNS C 111.143.18.172.in-addr.arpa. Internet PTR ? 6 0.00548 192.175.48.42 -> 207.88.152.10 ICMP Destination unreachable (UDP port 53 unreachable) 7 0.68462 207.88.152.10 -> 192.175.48.42 DNS C 69.160.18.172.in-addr.arpa. Internet PTR ? 8 0.00623 192.175.48.42 -> 207.88.152.10 ICMP Destination unreachable (UDP port 53 unreachable) 9 0.60348 207.88.152.10 -> 192.175.48.6 DNS C 52.143.18.172.in-addr.arpa. Internet PTR ? 10 0.00523 192.175.48.6 -> 207.88.152.10 ICMP Destination unreachable (UDP port 53 unreachable) Looks like the hosts are up but not listening on 53/udp? Anyone else seeing this? Heard about it? (Of course, the fix is to claim authority for the RFC1918 space you are using in your own DNS servers.) -- Crist J. Clark crist.clark@globalstar.com Globalstar Communications (408) 933-4387