Ping

auos

Hi,

Maybe my question is silly but it is question, suppose my PC has 3 NIC cards, each card has its own IP address and default gateway. If I do ping from my PC to any destination not in rang of any 3 NIC cards IP, did OS broadcast ping to all NICs and accept request for one of them.

Bl8ckr0uter

auos wrote: »

Hi,

Maybe my question is silly but it is question, suppose my PC has 3 NIC cards, each card has its own IP address and default gateway. If I do ping from my PC to any destination not in rang of any 3 NIC cards IP, did OS broadcast ping to all NICs and accept request for one of them.

Broadcast should only go out to the particular subnet so I would say no.

M4verick

auos wrote: »

Hi,

Maybe my question is silly but it is question, suppose my PC has 3 NIC cards, each card has its own IP address and default gateway. If I do ping from my PC to any destination not in rang of any 3 NIC cards IP, did OS broadcast ping to all NICs and accept request for one of them.

Just to clarify, I think you're saying that if you have three NICs, set up for three different networks, and you attempt to ping a different network altogether, does it send a request out all three NICs.

My thinking on that is no, I'd imagine it'd have a default NIC it would choose to send traffic out of. If you're running WinXP/Vista, go to the command prompt and do a 'route print', whatever link has the 0.0.0.0/0 default network should be the one it's pinging out.

Met44

If you have conflicting default routes with equal metrics on your PC, my experience is that your traffic not answered up for by another route will never be forwarded. This can be a problem when you have a wired and wireless interface and both of them pull DHCP information. As suggested above, you can use your OSes respective commands to view the routing table and delete one of the routes to get connectivity in this situation.

jason_lunde

wireshark it...

auos

Dears,
Many thanks for replays.

Gogousa

In windows, if you have more than one gateway and both have the same metric, windows will use the order of the connections that is set in:
Network Connections-->Advanced-->Advanced Setings...-->Adapters and Bindings-->Connections:
This way you prioritize a network card over other ones.

auos

Gogousa wrote: »

In windows, if you have more than one gateway and both have the same metric, windows will use the order of the connections that is set in:
Network Connections-->Advanced-->Advanced Setings...-->Adapters and Bindings-->Connections:
This way you prioritize a network card over other ones.

You are great.

M4verick

Gogousa wrote: »

In windows, if you have more than one gateway and both have the same metric, windows will use the order of the connections that is set in:
Network Connections-->Advanced-->Advanced Setings...-->Adapters and Bindings-->Connections:
This way you prioritize a network card over other ones.

Yeah, that's awesome. I've never seen that before.

malcybood

Also, if you knew which NIC you wanted traffic to exit for particular networks, you can add a static / persistent route to the host at the command line.

open a command prompt and type route print and it'll show you default gateways for destination networks including the default route.

If you add a persistent route to a multi-homed production server, ensure you add the -P switch at the end of the command. Many times I've seen servers rebooted after patching and it loses connectivity to certain parts of the network if this is not done.

Example command

route ADD 157.0.0.0 MASK 255.0.0.0 157.55.80.1 -P