Static routes are manually configured paths in a router’s routing table, giving precise control over traffic flow. Unlike dynamic routing protocols such as EIGRP or OSPF, static routes suit small networks and backup scenarios particularly well. A floating static route takes that idea further: it’s a backup path configured with a higher administrative distance (AD) than the primary route, so it only activates once the primary route fails — due to a link outage, a misconfiguration, or any other reason the primary path stops working.
For CCNA and CCNP study, mastering floating static routes matters both for exam questions and for real network resilience. This guide walks through configuration, verification, and troubleshooting using a sample topology with Router3, Router1, and Router2.
Network administrators use floating static routes to provide an automatic backup path to a primary static or dynamic route in case of a link failure. A floating static route only becomes active when the primary route is unavailable. When multiple paths to the same destination exist in the routing table, the router always picks the one with the lowest administrative distance — that’s the entire mechanism a floating static route relies on.
The default administrative distance of EIGRP is 90, so a floating static route meant to back up an EIGRP route must be configured with an AD higher than 90. If the floating route were configured with a lower value than 90, the router would use that static route first instead of EIGRP, defeating the purpose entirely.
Topology and Configuration
In this topology, a host reaches a web server through Router3, which has two available paths: a primary route through Router1, and a backup floating route through Router2. Router3 is configured with a default static route to Router1 with the default AD of 1. The floating static route to Router2 is configured with an AD of 3, ensuring it only activates if the primary route fails.
Router3> enable
Router3# configure terminal
Router3(config)# ip route 0.0.0.0 0.0.0.0 FastEthernet0/0 1
Router3(config)# ip route 0.0.0.0 0.0.0.0 FastEthernet0/1 3
Router3(config)# exit
Router3# write memoryThe first line is the primary route to Router1, with an explicit AD of 1 — matching the default, so it’s really just being made explicit for clarity. The second line is the floating route to Router2, given an AD of 3, which keeps it inactive as long as the primary route is up.
A note on best practice: this example points the static route directly at an exit interface (FastEthernet0/0, FastEthernet0/1) rather than at a next-hop IP address. That works fine in a simple lab, but on a genuine multi-access Ethernet segment it’s generally better practice to point a static route at the next-hop IP address instead. Pointing a static route at a broadcast-capable interface can trigger proxy ARP for every destination in that route and adds unnecessary ARP overhead — a detail worth knowing even though it doesn’t stop the lab example above from working as shown.
In this topology, the host has two possible paths to reach the web server. Router3 has two default static routes configured: one at the default administrative distance and one at an AD of 3. Router3 normally sends data to the web server via Router1, since that route uses the default AD value of 1. The route pointing to Router2, with its AD of 3, is the floating static route — present in the configuration but not actively used while the primary path is healthy.
When a problem occurs on the primary path, the router automatically removes that route from the active routing table and installs the floating static route in its place, so traffic to the web server shifts over to the floating route without any manual intervention.
Administrative Distance Values
Administrative Distance indicates how trustworthy a router considers a route source, with lower values preferred over higher ones:
| Source | Administrative Distance |
|---|---|
| Connected | 0 |
| Static | 1 |
| External BGP (eBGP) | 20 |
| Internal EIGRP | 90 |
| IGRP | 100 |
| OSPF | 110 |
| IS-IS | 115 |
| RIP | 120 |
| External EIGRP | 170 |
| Internal BGP (iBGP) | 200 |
IGRP is included here for completeness against the classic AD reference table, though it’s a legacy Cisco protocol that’s been removed from current IOS releases — you won’t configure it in a modern lab, but the AD value still appears on CCNA reference sheets.
For a floating static route to back up EIGRP (internal AD 90), configure the floating route with an AD higher than 90 — for example, 95.
Verifying Floating Static Routes
Check the active route on Router3:
Router3# show ip routeExpected output with the primary route active:
Gateway of last resort is 0.0.0.0 to network 0.0.0.0
S* 0.0.0.0/0 [1/0] via FastEthernet0/0The floating route (AD 3) doesn’t appear here at all — it stays out of the active routing table entirely while the primary route is up.
To test the floating route, disconnect the cable between Router3 and Router1, then check the routing table again:
Router3# show ip routeExpected output with the floating route active:
Gateway of last resort is 0.0.0.0 to network 0.0.0.0
S* 0.0.0.0/0 [3/0] via FastEthernet0/1Use traceroute to confirm the path itself has actually shifted:
Router3# traceroute 192.168.1.1This should show the path now flowing through Router2 rather than Router1, confirming the floating route is not just present in the table but is actually carrying traffic.
Troubleshooting Floating Static Routes
Floating route not activating. If the backup route never appears after the primary link fails, check the AD value first. Confirm the floating route’s AD is genuinely higher than the primary route’s — for example, 3 versus 1 — using show ip route. A floating route configured with too low an AD will never take over, since the router will keep preferring it over the primary route or ignoring it entirely depending on how the values compare.
Primary route persisting after a failure. If the primary route stays in the routing table even after the link is actually down, a misconfiguration or a physical-layer issue may be preventing the router from detecting the failure. Test deliberately with shutdown on the primary interface, then check show ip route to confirm the router responds by removing the primary route and installing the floating one.
Incorrect interface reference. Confirm the interface referenced in the floating route matches the actual topology — for example, that FastEthernet0/1 really is the interface connected toward Router2. Use show running-config | section ip route to confirm exactly what’s configured versus what the topology requires.
(The reference “check the AD values” above links to a general website-security-checking article rather than a networking AD reference — a mismatched auto-link kept per site policy.)
Resolve most floating static route issues by adjusting AD values or correcting interface assignments, then re-verifying with show ip route after each change.
Floating Static Routes with a Next-Hop IP Address
The interface-based example above is common in CCNA labs, but production networks more often configure floating static routes with an explicit next-hop IP address instead of an exit interface — particularly on multi-access links where pointing at an interface can cause the proxy-ARP issue mentioned earlier.
Router3(config)# ip route 0.0.0.0 0.0.0.0 192.168.10.1 1
Router3(config)# ip route 0.0.0.0 0.0.0.0 192.168.20.1 3Here, 192.168.10.1 is Router1’s interface address and 192.168.20.1 is Router2’s interface address. The behavior is otherwise identical to the interface-based version: the router always prefers the AD-1 route to Router1 until that path becomes unreachable, at which point the AD-3 route to Router2 takes over automatically.
IPv6 Floating Static Route Example
The same concept applies to IPv6 using the ipv6 route command, with the administrative distance specified as the final argument:
Router3(config)# ipv6 route ::/0 2001:DB8:1::1 1
Router3(config)# ipv6 route ::/0 2001:DB8:2::1 3Verify with show ipv6 route, which will show the same kind of AD-based preference between the primary and floating routes as the IPv4 examples above.
Frequently Asked Questions
What is a floating static route, and how does it work?
A floating static route is a backup route configured with a higher administrative distance than the primary route, which ensures it activates only when the primary route fails. In the Router3 topology, a primary route to Router1 uses AD 1 while a floating route to Router2 uses AD 3; if the link to Router1 fails due to a cable issue or misconfiguration, Router3 removes the primary route from its active table and installs the floating route in its place, redirecting traffic automatically.
How do I configure a floating static route on a Cisco router?
Enter global configuration mode, configure the primary route with a lower AD — for example, ip route 0.0.0.0 0.0.0.0 FastEthernet0/0 1 for the path via Router1 — then add the floating route with a higher AD, such as ip route 0.0.0.0 0.0.0.0 FastEthernet0/1 3 for the path via Router2. The higher AD on the second route keeps it inactive unless the primary route disappears from the table. Save the configuration with write memory and confirm with show ip route, since this hands-on skill is a common CCNA and CCNP exam topic.
What administrative distance should I use for a floating static route?
The AD for a floating static route always needs to exceed the primary route’s AD. Since the default AD for a static route is 1, a floating route needs an AD of 2 or higher — 3 is a common lab value. If the floating route is backing up a dynamic protocol instead, such as EIGRP at AD 90, the floating route’s AD needs to be set above that value, for example 95, so the dynamic route still wins under normal conditions.
How can I verify if a floating static route is working?
Run show ip route on Router3 to check which route is currently active. With the primary route up, only that route appears in the table — for example, S* 0.0.0.0/0 [1/0] via FastEthernet0/0. After disconnecting the primary link and re-running the command, the floating route should now appear instead, showing its higher AD value, such as S* 0.0.0.0/0 [3/0] via FastEthernet0/1. Following up with traceroute confirms the actual traffic path has shifted, not just the routing table entry.
What should I do if my floating static route doesn’t activate?
First confirm with show ip route that the floating route’s AD is genuinely higher than the primary route’s — for example, 3 versus 1 — since a misconfigured AD is the most common cause of this problem. Next, verify the interface or next-hop referenced in the floating route actually matches the topology, using show running-config | section ip route to check the exact configuration. If the primary route still isn’t failing over even with a correct AD, test by manually shutting down the primary interface to confirm the router removes it from the active table as expected — this isolates whether the issue is the AD configuration itself or a failure-detection problem on the primary path.
