i was trying to ping the broadcast address of my subnet n this is the output:
[root@vijay ~]# ping -b 172.31.83.255
WARNING: pinging broadcast address
PING 172.31.83.255 (172.31.83.255) 56(84) bytes of data.
64 bytes from 172.31.80.2: icmp_seq=1 ttl=255 time=0.442 ms
64 bytes from 172.31.80.1: icmp_seq=1 ttl=255 time=0.483 ms (DUP!)
64 bytes from 172.31.80.4: icmp_seq=1 ttl=64 time=0.989 ms (DUP!)
64 bytes from 172.31.80.5: icmp_seq=1 ttl=255 time=98.5 ms (DUP!)
64 bytes from 172.31.80.4: icmp_seq=2 ttl=64 time=0.215 ms
64 bytes from 172.31.80.2: icmp_seq=2 ttl=255 time=4.82 ms (DUP!)
64 bytes from 172.31.80.1: icmp_seq=2 ttl=255 time=4.87 ms (DUP!)
64 bytes from 172.31.80.5: icmp_seq=2 ttl=255 time=28.4 ms (DUP!)
64 bytes from 172.31.80.4: icmp_seq=3 ttl=64 time=0.217 ms
64 bytes from 172.31.80.2: icmp_seq=3 ttl=255 time=4.34 ms (DUP!)
64 bytes from 172.31.80.1: icmp_seq=3 ttl=255 time=4.39 ms (DUP!)
64 bytes from 172.31.80.5: icmp_seq=3 ttl=255 time=13.0 ms (DUP!)
--- 172.31.83.255 ping statistics ---
3 packets transmitted, 3 received, +9 duplicates, 0% packet loss, time 1999ms
rtt min/avg/max/mdev = 0.215/13.404/98.573/26.810 ms
unfortunately,it didn't happen as expected i had to get reply from all hosts those were up right..
this differs from nmap's ping sweep output on my subnet..
here's my ifconfig and routing table:
[root@vijay ~]# ifconfig eth0
eth0 Link encap:Ethernet HWaddr 00:16:76:4B:9B:0C
inet addr:172.31.80.194 Bcast:172.31.83.255 Mask:255.255.252.0
inet6 addr: fe80::216:76ff:fe4b:9b0c/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:29055 errors:0 dropped:0 overruns:0 frame:0
TX packets:9596 errors:0 dropped:0 overruns:0 carrier:0
RX bytes:2988379 (2.8 MiB) TX bytes:770561 (752.5 KiB)
[root@vijay ~]# netstat -rn
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
172.31.80.0 0.0.0.0 255.255.252.0 U 0 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0
0.0.0.0 172.31.80.1 0.0.0.0 UG 0 0 0 eth0
plzz help me... i am a networking newbie presently studying broadcasting..
thnx in advance..