use ping at flame.cs.columbia.edu (128.59.16.145)

: flame.cs.columbia.edu ;ping -P 0x04  bart.cs.columbia.edu
bart.cs.columbia.edu is alive
: flame.cs.columbia.edu ;

//-------------------------------------------------------------------------------
Run tcpdump at bart.cs.columbia.edu (128.59.19.191)


: bart.cs.columbia.edu ;tcpdump -n -v -v
tcpdump: listening on hme0
19:15:30.989207 128.59.16.145 > 128.59.19.191: icmp: echo request (DF) [tos 0x4]  (ttl 255, id 21289, len 84)
19:15:30.989236 128.59.19.191 > 128.59.16.145: icmp: echo reply (DF) [tos 0x4]  (ttl 255, id 8631, len 84)