How does software know which NIC to use

lets say i have 2 NIC in my machine. one configured to use 10.10.10.0
network
and another configured to use 192.168.1.0 network. Now lets say I open
Internet Explorer. How does this program knows which card to use? How
do I force it to use 10.10.10.0 network instead of 192.168.1.0 network.


Thanks a bunch in advance to anyone who would be kind enough to explain this
to me.

There are 2 ways of doing this.

1: under both adapter tcp/ip settings set the default gateway as "1010.10.1"
(assuming .1 is your default gateway).

2: add a persistant route in your routing table to forward the specific
traffic through a specific interface. at a command prompt, type "route help"
to get the syntax.


hope this helps.

Mike
"asdf" wrote:

> lets say i have 2 NIC in my machine. one configured to use 10.10.10.0
> network
> and another configured to use 192.168.1.0 network. Now lets say I open
> Internet Explorer. How does this program knows which card to use? How
> do I force it to use 10.10.10.0 network instead of 192.168.1.0 network.
>
>
> Thanks a bunch in advance to anyone who would be kind enough to explain this
> to me.
>
>
>

What you are really asking is "how does IP routing work".

If the target machine's address is in the same IP subnet as one of the
machine's NICs, the traffic will go via that NIC. It uses direct delivery
(ie it sends "on the wire" using hardware addressing).

If the target is not in the same IP subnet as a NIC, the routing table
will be checked to look for a route to the target's IP subnet. If there is
more than one, the most specific will be used. The route includes the
address of the NIC to use. If there is no specific route, the traffic will
be sent to the NIC which is in the same subnet as the default router
(sometimes called the default gateway).

asdf wrote:
> lets say i have 2 NIC in my machine. one configured to use 10.10.10.0
> network
> and another configured to use 192.168.1.0 network. Now lets say I open
> Internet Explorer. How does this program knows which card to use? How
> do I force it to use 10.10.10.0 network instead of 192.168.1.0
> network.
>
>
> Thanks a bunch in advance to anyone who would be kind enough to
> explain this to me.

"asdf" <(E-Mail Removed)> wrote in message news:Jj34e.6356$(E-Mail Removed)...
> and another configured to use 192.168.1.0 network. Now lets say I open
> Internet Explorer. How does this program knows which card to use?

"Software" doesn't know.
It just passes what it is doing to the TCP/IP Stack and doesn't care what
happens to it after that. What happens after that is determined as Bill and
Michael have described.

--

Phillip Windell [MCP, MVP, CCNA]
www.wandtv.com