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CCNA 3.8.a: Default route

Overview:

A default route is used to route traffic to any network that is not in your routing table.

Without a default route defined, any traffic destined to a network that is not in the routing table will be dropped by the router.

Study Notes:

• A default route is configured to route packets to networks that are not in your routing table
• Without a default route, the destination address must match an address in your routing table, otherwise the packets will be dropped by the router
• Typically, the default route points to the internet
• A default route puts the onus of routing on the next hop router.
• Most often the default route is an upstream router.
• It's like a router saying I don't know how to get to that destination, but my default route says to send it to this next hop so I'll make it that router's job to figure it out.
• A default route identifies the gateway IP address to which the router sends all IP packets for which it does not have a learned or static route.
• A default static route is simply a static route with 0.0.0.0/0 as the destination IP address.
• Routes that identify a specific destination take precedence over the default route.

• Configure an IPv4 default route by typing:

config t
    ip route 0.0.0.0 0.0.0.0 <exit-interface-on-this-router>
    --OR--
    ip route 0.0.0.0 0.0.0.0 <next-hops-ipv4-address>

• Configure an IPv6 default route by typing:

config t
    ipv6 route ::/0 <exit-interface-on-this-router>
    --OR--
    ipv6 route ::/0 <next-hop-ipv6-address>

Labs:

PacketTracer Lab: CCNA-3.8.a-Default-route.pkt

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