Check your ARP tables, local and on intervening switches/routers. Make sure there are no duplicate entries for that IP. If you note the response time, the second packet is always higher which might be indicative. I would also check for a botched MITM a la C&A. Even if there is no obvious ARP table manglement, you might try flushing the local and intervening caches. Try the ping from another host, another subnet, another segment, get more info. --p -----Original Message----- From: chloe K [mailto:chloekcy2000@yahoo.ca] Sent: Wednesday, September 10, 2008 6:46 AM To: nanog@nanog.org Subject: duplicate packet Hi all When I ping the ip, I get the duplicate I check the ip is just one. Why it happens? Thank you 64 bytes from 192.168.0.95: icmp_seq=1 ttl=63 time=0.344 ms 64 bytes from 192.168.0.95: icmp_seq=1 ttl=63 time=0.401 ms (DUP!) 64 bytes from 192.168.0.95: icmp_seq=2 ttl=63 time=0.296 ms 64 bytes from 192.168.0.95: icmp_seq=2 ttl=63 time=0.328 ms (DUP!) 64 bytes from 192.168.0.95: icmp_seq=3 ttl=63 time=0.291 ms 64 bytes from 192.168.0.95: icmp_seq=3 ttl=63 time=0.316 ms (DUP!) 64 bytes from 192.168.0.95: icmp_seq=4 ttl=63 time=0.279 ms 64 bytes from 192.168.0.95: icmp_seq=4 ttl=63 time=0.309 ms (DUP!) 64 bytes from 192.168.0.95: icmp_seq=5 ttl=63 time=0.271 ms 64 bytes from 192.168.0.95: icmp_seq=5 ttl=63 time=0.299 ms (DUP!) --------------------------------- Yahoo! Canada Toolbar : Search from anywhere on the web and bookmark your favourite sites. Download it now!