It is absolutely critical that you understand how IP itself works before you try to understand IP routing. If you don't understand the basics of IP, you should go back and learn it now.
THE LAWS OF IP
- The Default Gateway is for reaching OFF NETWORK hosts (hosts not on the local subnet).
- Default gateways are used for contacting hosts external to the local subnet, NOT for contacting hosts on the same subnet.
- You route TO DESTINATIONS, not from sources.
- Routing is not used on a local subnet.
- Internet Protocol should not forward broadcasts off the local subnet. This is a congestion control mechanism built into most IP routers.
- Routing is not used for hardware broadcasts which by definition are local traffic (ARP, DHCP, NetBIOS, NetBEUI etc.) see RFC 919.
- The broadcast address 255.255.255.255 SHOULD NOT BE FORWARDED (per RFC 919, section 7.0). If such forwarding were broadly permitted, the Internet would be flooded with broadcast traffic.
For a more complete tutorial, click HERE.
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