An enterprise edge router R1 connects to two distinct Internet Service Providers via Ether… — Cisco CCNA

An enterprise edge router R1 connects to two distinct Internet Service Providers via Ethernet interfaces. The network team requires primary outbound traffic to traverse ISP-1 via next-hop IPv4 address $203.0.113.1/30$ on interface GigabitEthernet0/0/1. A backup path must traverse ISP-2 via next-hop IPv4 address $198.51.100.1/30$ on interface GigabitEthernet0/0/2, taking effect only if the primary route fails.

Which two configuration statements or operational characteristics are correct for implementing this routing strategy?

Configuring `ip route 0.0.0.0 0.0.0.0 203.0.113.1` creates the primary default route with an implicit Administrative Distance of $1$ .Answer
Configuring `ip route 0.0.0.0 0.0.0.0 198.51.100.1 130` establishes a floating static route that remains inactive in the routing table while the primary route is reachable.Answer
C
Configuring `ip route 0.0.0.0 0.0.0.0 198.51.100.1 1` configures the secondary route as a floating backup by matching the administrative distance of the primary route.
D
Configuring `ip route 0.0.0.0 0.0.0.0 GigabitEthernet0/0/2` for the backup route eliminates the need for Proxy ARP on the ISP-2 router.

Answer

The primary default static route is configured with `ip route 0.0.0.0 0.0.0.0 203.0.113.1` using the default Administrative Distance of 1, while the backup default route is configured with `ip route 0.0.0.0 0.0.0.0 198.51.100.1 130` with a higher Administrative Distance to serve as a floating backup.

The command defining the primary static route uses the standard `ip route 0.0.0.0 0.0.0.0 <next-hop>` syntax, which automatically assigns a default Administrative Distance of 1. The command setting the floating static backup specifies an Administrative Distance of 130, which is higher than the primary route's AD of 1, ensuring it is installed in the active forwarding table only when the primary path becomes unreachable.

Step-by-Step Solution

Analyze primary route configuration syntax and Administrative Distance default values.

The command `ip route 0.0.0.0 0.0.0.0 203.0.113.1` creates a default static route pointing to next-hop

203.0.113.1

. By default, IPv4 static routes have an Administrative Distance of

1

Default static routes require an administrative distance lower than backup routes to be installed in the routing table first.

Evaluate requirements for a floating static route.

A floating static route must have its Administrative Distance manually configured to a value higher than the primary route (e.g.,

130 > 1

Cisco IOS selects routes with the lowest Administrative Distance. Higher AD static routes remain in the running configuration but are hidden from the active IP routing table until the primary route drops.

Examine errors in alternative configuration choices.

Using an AD of

1

for the secondary route results in equal-cost routes rather than a backup. Specifying only an Ethernet exit interface without a next-hop IP forces the router to perform ARP requests for every internet destination address, requiring Proxy ARP on the ISP peer.

Ethernet is a multiaccess medium; without a next-hop IPv4 address specified, destination IP-to-MAC resolution relies on Proxy ARP.

Key Concept

IPv4 Default and Floating Static Route Configuration Mechanics

Question

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

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