Recursive route

As explained in Acing the CCNA Exam: Volume 1 Fundamentals and Protocols

A recursive route is a route that specifies a next-hop IP address without specifying the outgoing interface.

A recursive route specifies a destination and a next-hop IP address, but no outgoing interface. The router must use that next-hop address to determine where to forward packets. section 9.3.2

Distinguish route types by what they specify:

• A recursive route specifies only the next-hop IP address. section 9.3.2
• A directly connected route specifies only the exit interface. section 9.3.2
• A fully specified route specifies both the next-hop IP address and exit interface. section 9.3.2

Cisco static-route example

The command ip route 10.0.0.0 255.0.0.0 192.0.2.1 creates a network route and a recursive route: 10.0.0.0/8 is the destination network, and 192.0.2.1 is the only specified next hop. section 9.3.2

Figure 9.11 R1 has two routes to specific destination networks and one default route to the internet. (1) A route to 192.168.2.0/24, with R2 G0/0 as the next hop. (2) A route to 192.168.3.0/24, with R3 G0/0 as the next hop. (3) A default route, with the ISP’s IP address (203.0.113.2) as the next hop.

Compare recursive static routes to 192.168.2.0/24 and 192.168.3.0/24 with a recursive default route using the ISP’s next-hop address. section 9.3.2

How Acing the CCNA Exam: Volume 1 Fundamentals and Protocols covers it

How deep it goes

Distinguishes recursive, directly connected, and fully specified routes through definitions and an examined Cisco command.

Examples

Uses ip route 10.0.0.0 255.0.0.0 192.0.2.1 and a router diagram containing recursive network and default routes.

What it assumes

Assumes recognition of destination networks, next-hop IP addresses, and outgoing interfaces.

What you can do after

Apply it via the Cisco ip route command and identify recursive routes in CCNA-style questions.

How it connects

Connects recursive routes with static routes, default routes, next-hop IP addresses, and exit interfaces.

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Related concepts

• next hopuses · A next hop is the immediately subsequent router or forwarding destination to which a packet is sent along a route.
• routingkind of · Routing is the selection of a path, destination, or processing component to direct an item, request, or flow toward an intended endpoint.

This explainer was generated by Manning's knowledge graph from the text of Acing the CCNA Exam: Volume 1 Fundamentals and Protocols. The section links point to the parts of the book it draws on.