Floating Static Routes

38 questions

All types38 Multiple choice18 Multiple select10 Fill in the blank10

An engineer wants to configure a floating static route on a Cisco router to serve as a backup for a primary route learned via OSPF (Administrative Distance 110). Which two statements correctly describe the requirements and operational behavior of this floating static route?

Select all that apply

The administrative distance assigned to the floating static route must be set higher than 110.

The floating static route will remain inactive and out of the routing table as long as the primary OSPF route is active.

The administrative distance of the floating static route must be set lower than 110 to ensure backup capability.

The floating static route automatically balances traffic with the OSPF route when configured with the default distance of 1.

Show answer & explanation

Answer: The administrative distance assigned to the floating static route must be set higher than 110.; The floating static route will remain inactive and out of the routing table as long as the primary OSPF route is active.

Answer

The floating static route must be configured with an administrative distance greater than 110, and it will remain inactive in the routing table while the primary OSPF route is operational.

A floating static route functions as a backup and must be configured with an administrative distance higher than that of the active primary routing protocol (OSPF AD 110). Because Cisco routers select routes with lower administrative distance values for forwarding, the floating static route remains hidden from the routing table until the primary OSPF route fails.

Step-by-Step Solution

Determine the administrative distance of the primary route.

OSPF has a default administrative distance of 110.

To create a floating static backup route, the configured administrative distance must be higher than that of the primary route.

Analyze router path selection logic.

The router selects the route with the lowest administrative distance for installation into the active routing table.

Because the static route's administrative distance is higher than 110, it stays out of the routing table until the primary OSPF route disappears.

Key Concept

Floating Static Route Administrative Distance Requirements

Estimated Time:1m 0s

Question 2Question →

A router receives its primary path to the 172.20.0.0/16 subnet via internal EIGRP. Which administrative distance value should be configured on a static route to ensure it functions as an inactive floating backup route until the primary path fails?

Show answer & explanation

Answer: 95

Answer

An administrative distance value of 95 should be specified for the static route.

A floating static route is designed to serve as a backup path that only installs into the IP routing table when the primary route fails. Router forwarding decisions prioritize routes with lower administrative distance (AD) values. Internal EIGRP has a default AD of 90. Assigning a value of 95 ensures the static route has a higher AD than the primary EIGRP route, keeping it dormant until EIGRP route failure occurs.

Step-by-Step Solution

Identify the administrative distance of the primary routing protocol.

Internal EIGRP has a default administrative distance (AD) of 90.

Routers use administrative distance to evaluate trustworthiness when selecting the best path among different routing sources.

Determine the required administrative distance for a floating static backup route.

The backup static route must have an AD greater than 90 (e.g., 95).

A floating static route remains inactive in the routing table only if its administrative distance is higher than that of the active primary routing protocol.

Key Concept

Floating Static Route Administrative Distance

Estimated Time:45s

Question 3Question →

A network router receives its primary path to a corporate office via external BGP with an administrative distance of 20. Which administrative distance value should be assigned to a static backup route to ensure it functions as a floating static route?

Show answer & explanation

Answer: 50

Answer

An administrative distance of 50 should be assigned.

A floating static route must have an administrative distance higher than the primary route so it is ignored by the routing table during normal operation and only installed if the primary route fails. Since the primary eBGP route has an administrative distance of 20, setting the static route's administrative distance to 50 makes it a valid backup route.

Step-by-Step Solution

Identify the administrative distance of the primary route.

The primary route is learned via external BGP, which has an administrative distance of 20.

Routing protocols use administrative distance to rank trustworthiness, preferring lower values.

Determine the required administrative distance for a floating static route.

The static route must be configured with an administrative distance greater than 20.

Floating static routes act as backups and must remain inactive in the routing table until the primary route with a lower administrative distance becomes unavailable.

Select the valid administrative distance option.

50 is greater than 20, making it a valid floating static route distance.

A value of 50 ensures the static route is only placed into the routing table if the eBGP route fails.

Key Concept

Floating static routes require a higher administrative distance than the primary routing protocol to remain inactive as a backup until failover occurs.

Question 4Question →

A router learns the destination network $10.20.30.0/24$ dynamically via RIPv2 with a default Administrative Distance of $120$ . A network engineer needs to configure a floating static backup route for this network via next-hop IP address $192.168.12.2$ . The backup route must only enter the routing table if the primary RIP route fails. Complete the Cisco IOS configuration command to assign an Administrative Distance of $130$ to the floating static route.

Fill in the blanks below

Router(config)# ip route 10.20.30.0 255.255.255.0 192.168.12.2

Show answer & explanation

Answer

130

A floating static route serves as a backup path and must be configured with an Administrative Distance (AD) strictly higher than that of the primary route. Since RIPv2 has a default AD of 120, specifying 130 as the trailing metric in the 'ip route' command ensures that the static route remains out of the routing table until the RIP route fails.

Step-by-Step Solution

Identify the Administrative Distance (AD) of the primary dynamic routing protocol.

RIPv2 has a default Administrative Distance of 120.

Routing decisions prioritize routes with lower Administrative Distance values.

Determine the required Administrative Distance for the backup floating static route.

The backup route must have an AD greater than 120 (specifically 130 as requested).

A higher AD keeps the static route inactive (floating) in the routing table as long as the primary route is active.

Complete the Cisco IOS command by appending the administrative distance integer at the end.

The trailing argument in 'ip route 10.20.30.0 255.255.255.0 192.168.12.2 130' sets the AD to 130.

In Cisco IOS syntax, an optional integer at the end of the 'ip route' command overrides the default static route AD of 1.

Key Concept

Floating Static Route Administrative Distance Configuration

Estimated Time:1m 0s

Question 5Question →

Router R1 learns the destination prefix $172.16.10.0/24$ dynamically via OSPF with a default Administrative Distance of 110. A network administrator needs to implement a floating static route to $172.16.10.0/24$ via next-hop IP $192.168.12.2$ to serve as a backup path.

Which TWO statements correctly describe the configuration requirements and routing table behavior for this floating static route? (Select TWO.)

Select all that apply

The floating static route must be configured with an Administrative Distance greater than 110 (such as 120).

The floating static route remains in R1's running configuration but is excluded from the active routing table while the primary OSPF route is active.

Configuring an Administrative Distance of 90 for the static route ensures it functions as an inactive backup route until OSPF fails.

If the static route is assigned an Administrative Distance equal to 110, the router will perform equal-cost load balancing between OSPF and the static route.

Show answer & explanation

Answer: The floating static route must be configured with an Administrative Distance greater than 110 (such as 120).; The floating static route remains in R1's running configuration but is excluded from the active routing table while the primary OSPF route is active.

Answer

The floating static route must be configured with an Administrative Distance higher than the primary routing protocol (greater than 110 for OSPF), and it will remain stored in the router configuration without appearing in the routing table until the primary route fails.

A floating static route acts as a backup path and is created by manually configuring a static route with an Administrative Distance higher than that of the primary routing protocol. Since the primary route is OSPF with an AD of 110, setting the static route AD higher (e.g., 120) prevents it from being installed in the active routing table under normal operating conditions. It remains stored in the router configuration and is installed into the routing table only if the primary OSPF route disappears.

Step-by-Step Solution

Identify the Administrative Distance (AD) of the primary path protocol.

OSPF has a default Administrative Distance of 110.

Administrative Distance indicates the trustworthiness of the route source. Lower AD values are preferred.

Determine the AD required for a floating static backup route.

The AD must be set to a value strictly greater than 110 (e.g., 120 or 130).

Setting the AD higher ensures the static route is less preferred than OSPF during normal network operations.

Analyze how Cisco IOS processes inactive floating static routes.

The backup static route is maintained in the running configuration but omitted from the active IP routing table.

The routing table only installs the route with the lowest AD for any given destination network prefix.

Key Concept

Floating Static Route Administrative Distance Requirements

Question 6Question →

A network administrator needs to configure a backup static route to destination network 192.168.50.0/24 via next-hop IP address 10.1.1.2. The primary route to this network is learned dynamically through OSPF, which has a default administrative distance of 110. Which command correctly configures a floating static route that remains inactive in the routing table until the primary OSPF route fails?

ip route 192.168.50.0 255.255.255.0 10.1.1.2 120

ip route 192.168.50.0 255.255.255.0 10.1.1.2 90

ip route 192.168.50.0 255.255.255.0 10.1.1.2

ip route 192.168.50.0 255.255.255.0 10.1.1.2 100

Show answer & explanation

Answer: ip route 192.168.50.0 255.255.255.0 10.1.1.2 120

Answer

The command 'ip route 192.168.50.0 255.255.255.0 10.1.1.2 120' correctly configures the floating static route.

A floating static route acts as a backup path and must be configured with an administrative distance higher than the primary route's protocol. Because OSPF has a default administrative distance of 110, setting the static route's administrative distance to 120 ensures it stays out of the routing table until the primary OSPF path fails.

Step-by-Step Solution

Determine the administrative distance of the primary routing protocol

OSPF has a default administrative distance of 110.

A floating static route must have a higher administrative distance than the primary route to remain inactive while the primary route is operational.

Select an administrative distance value for the static route higher than 110

The value 120 is greater than 110.

Specifying 120 at the end of the 'ip route' command creates a floating static route that only enters the routing table if the OSPF route (110) disappears.

Key Concept

Floating Static Routes and Administrative Distance

Question 7Question →

Complete the Cisco IOS command below to configure a floating static route for the 172.16.100.0/22 network using the next-hop address 10.254.1.2. The route must serve as a floating backup to a primary path learned via internal EIGRP. Enter the dotted-decimal subnet mask in the first blank and the minimum integer administrative distance value required for backup operation in the second blank.

Fill in the blanks below

ip route 172.16.100.0 10.254.1.2

Show answer & explanation

Answer

blank_1: 255.255.252.0, blank_2: 91

To configure a floating static route in Cisco IOS for the 172.16.100.0/22 prefix, the subnet mask must be specified in dotted-decimal format as 255.255.252.0. Internal EIGRP operates with a default Administrative Distance of 90. To ensure the static route acts strictly as a floating backup—entering the routing table only when the primary EIGRP route is lost—the static route must be assigned an Administrative Distance greater than 90. The minimum integer value that achieves this is 91.

Step-by-Step Solution

Convert the CIDR prefix length /22 to a dotted-decimal subnet mask.

A /22 prefix corresponds to 22 contiguous network bits (11111111.11111111.11111100.00000000), which equals 255.255.252.0.

Cisco IOS IPv4 static route syntax requires the subnet mask in dotted-decimal notation.

Identify the default Administrative Distance (AD) of internal EIGRP.

Internal EIGRP has a default AD of 90.

A floating static route must have an AD strictly greater than the primary route's AD to remain inactive in the routing table while the primary path is reachable.

Calculate the minimum administrative distance for the floating static route.

The minimum integer value greater than 90 is 91.

Assigning an AD of 91 ensures the static route is floating (inactive) relative to EIGRP (AD 90) but activates immediately if the EIGRP route fails.

Key Concept

Floating Static Route Configuration and Administrative Distance

Estimated Time:2m 0s

Question 8Question →

A network administrator needs to configure a backup floating static route for destination network 10.30.0.0/16 via next-hop IP 192.168.10.2. The primary route to this destination is learned via internal EIGRP, which has a default administrative distance of 90. What is the minimum administrative distance value that must be specified at the end of the command to ensure the route acts as a backup?

Fill in the blanks below

`Router(config)# ip route 10.30.0.0 255.255.0.0 192.168.10.2 `

Show answer & explanation

Answer

To configure a floating static route, the administrative distance (AD) appended to the end of the `ip route` command must be higher than the AD of the primary route. Because internal EIGRP has an administrative distance of 90, the minimum integer value required to make the static route act as a backup is 91.

Step-by-Step Solution

Identify the administrative distance (AD) of the primary routing protocol.

Internal EIGRP has a default Administrative Distance of 90.

Floating static routes rely on administrative distance values to determine route preference in the Cisco IOS routing table.

Determine the required administrative distance for the backup static route.

The floating static route must have an AD strictly greater than 90.

A route with a lower AD is always preferred. Standard static routes have a default AD of 1, which would override EIGRP if not changed.

Calculate the minimum integer value.

The lowest integer greater than 90 is 91.

Setting the AD to 91 ensures EIGRP is preferred under normal operations while allowing the static route to take over if EIGRP fails.

Key Concept

Floating Static Route Administrative Distance Configuration

Question 9Question →

An enterprise router receives an internal EIGRP route for the summary prefix 172.16.0.0/16 (Administrative Distance 90) and learns a specific path for subnet 172.16.10.0/24 via OSPF (Administrative Distance 110). A network engineer attempts to configure a backup floating static route for destination 172.16.10.0/24 using the command `ip route 172.16.10.0 255.255.255.0 192.168.1.2 100`. Under normal operating conditions while all links remain fully operational, which routing behavior will occur for traffic sent to host 172.16.10.50?

The router routes traffic using the static route via next-hop 192.168.1.2 because its Administrative Distance of 100 is lower than the OSPF route's Administrative Distance of 110.

The router routes traffic using the EIGRP route because EIGRP has a lower Administrative Distance (90) than the configured static route (100).

The router load-balances traffic equally between the OSPF path and the static path because both match the /24 destination prefix.

The static route remains inactive in the RIB and only enters the routing table if the OSPF neighbour adjacency fails.

Show answer & explanation

Answer: The router routes traffic using the static route via next-hop 192.168.1.2 because its Administrative Distance of 100 is lower than the OSPF route's Administrative Distance of 110.

Answer

Traffic to host 172.16.10.50 will be forwarded using the static route via next-hop 192.168.1.2 because its configured Administrative Distance of 100 is lower than OSPF's Administrative Distance of 110.

For identical prefix lengths (/24), the router compares Administrative Distance (AD) values to determine which route enters the routing table. OSPF has a default AD of 110. Since the configured static route has an AD of 100, which is lower than 110, Cisco IOS selects the static route as the active primary path. Consequently, traffic destined for 172.16.10.50 is immediately forwarded via next-hop 192.168.1.2.

Step-by-Step Solution

Evaluate the prefix lengths available for the destination address 172.16.10.50.

Two prefix lengths match: /16 (EIGRP summary) and /24 (OSPF and static). The longest prefix match rule prioritizes the /24 subnet over the /16 summary.

Cisco routers always select the most specific route (longest subnet mask) first during packet forwarding lookup.

Compare the Administrative Distance (AD) values of competing routes for the 172.16.10.0/24 destination.

The OSPF route has a default AD of 110, while the configured static route has an AD of 100.

When multiple sources offer a route to the exact same prefix, Cisco IOS selects the route with the lowest Administrative Distance to install into the Routing Information Base (RIB).

Determine the operational status of the floating static route.

Because AD 100 < AD 110, the static route is active in the routing table immediately, preempting the primary OSPF route rather than acting as a floating backup.

A floating static route must have an AD set strictly higher than the primary route (e.g., AD 115 or higher) to remain dormant until the primary route fails.

Key Concept

Floating Static Route Administrative Distance Selection

Question 10Question →

An enterprise edge router receives a primary internal route for destination prefix $10.50.0.0/16$ via Internal EIGRP (Administrative Distance 90) and a primary default route for $0.0.0.0/0$ via external BGP (eBGP, Administrative Distance 20). A network administrator needs to configure floating static routes to serve as automatic failover backups for both destinations. Which TWO configuration statements correctly specify the Administrative Distance requirements for these static routes to operate strictly as floating backups? (Select TWO.)

Select all that apply

The floating static route backing up destination

10.50.0.0/16

must be configured with an Administrative Distance value greater than 90.

The floating static route backing up destination

0.0.0.0/0

must be configured with an Administrative Distance value greater than 20.

The floating static route backing up destination

0.0.0.0/0

should use the default static Administrative Distance of 1 so it takes precedence during failure scenarios.

The floating static route backing up destination

10.50.0.0/16

should be configured with an Administrative Distance of 85 to prevent route flapping between routing processes.

Show answer & explanation

Answer: The floating static route backing up destination $10.50.0.0/16$ must be configured with an Administrative Distance value greater than 90.; The floating static route backing up destination $0.0.0.0/0$ must be configured with an Administrative Distance value greater than 20.

Answer

The floating static route for 10.50.0.0/16 must have an Administrative Distance greater than 90, and the floating static route for 0.0.0.0/0 must have an Administrative Distance greater than 20.

Cisco IOS routing table selection prioritizes routes with lower Administrative Distance (AD). For a static route to function as a 'floating' backup, its AD must be manually configured to a value higher than that of the active primary routing protocol (Internal EIGRP AD 90, eBGP AD 20). This ensures the static route remains untracked in the routing table until the primary route's AD source is lost.

Step-by-Step Solution

Identify the default Administrative Distance (AD) of the primary routing protocols.

Internal EIGRP has a default AD of 90; external BGP (eBGP) has a default AD of 20.

Cisco IOS selects routes with the lowest Administrative Distance when multiple sources provide routes to the same destination.

Determine the required AD for floating static backup routes.

Backup route AD for EIGRP must be > 90 (e.g., 95). Backup route AD for eBGP must be > 20 (e.g., 25).

A floating static route must remain out of the routing table while the primary protocol is active, which requires the static route to have a higher numerical AD than the primary route.

Key Concept

Floating Static Route Administrative Distance Requirements

Question 11Question →

A network administrator is configuring a backup floating static route to reach an external corporate subnet 172.31.50.0/24. The primary path to this destination is learned dynamically via External BGP (eBGP). During testing while the primary eBGP connection is fully operational, the administrator observes that traffic toward 172.31.50.0/24 is being forwarded across the backup static path rather than the primary link. Which static route command entry in the router configuration caused this improper failover behavior?

ip route 172.31.50.0 255.255.255.0 192.168.12.2 15

ip route 172.31.50.0 255.255.255.0 192.168.12.2 25

ip route 172.31.50.0 255.255.255.0 192.168.12.2 90

ip route 172.31.50.0 255.255.255.0 192.168.12.2 110

Show answer & explanation

Answer: ip route 172.31.50.0 255.255.255.0 192.168.12.2 15

Answer

The command 'ip route 172.31.50.0 255.255.255.0 192.168.12.2 15' sets the administrative distance lower than eBGP, causing it to preempt the primary route.

Cisco IOS assigns default Administrative Distance values to evaluate route trustworthiness. External BGP (eBGP) routes carry a default AD of 20. To create a floating static backup route for an eBGP path, the trailing administrative distance argument in the 'ip route' command must be set higher than 20. Specifying an administrative distance of 15 makes the static route more preferred than the eBGP route (15 < 20), causing the router to immediately install the static path into the routing table even when the eBGP link is active.

Step-by-Step Solution

Identify the Administrative Distance (AD) of the primary routing protocol.

External BGP (eBGP) has a Cisco default Administrative Distance of 20.

Administrative Distance determines route trustworthiness when multiple sources advertise the exact same network prefix.

Evaluate the requirement for a floating static route.

A floating static route must have an AD strictly greater than the primary route's AD (greater than 20) so it stays inactive until the primary route drops out of the routing table.

The router installs the route with the lowest AD into the IP routing table.

Analyze the configured static route entries to identify why the backup route preempted the primary path.

Configuring an administrative distance of 15 gives the static route a lower AD than eBGP (15 < 20).

Because 15 is lower than 20, the router selects the static route over the operational eBGP path.

Key Concept

Floating Static Route Administrative Distance relative to eBGP

Estimated Time:1m 30s

Question 12Question →

A network administrator is configuring a static backup route to take over if an existing primary route learned via OSPF (Administrative Distance 110) fails. Which TWO statements describe requirements for this floating static route to function correctly as a backup?

Select all that apply

The static route must be configured with an administrative distance value greater than 110.

The primary OSPF route must be removed from the routing table before the floating static route can be installed.

The static route must be configured with an administrative distance value lower than 110.

The static route must be configured with an administrative distance value equal to 110.

Show answer & explanation

Answer: The static route must be configured with an administrative distance value greater than 110.; The primary OSPF route must be removed from the routing table before the floating static route can be installed.

Answer

The static route must be configured with an administrative distance value greater than 110, and the primary OSPF route must be removed from the routing table before the floating static route can be installed.

A floating static route serves as a backup path by configuring an administrative distance higher than that of the primary route (greater than 110 for an OSPF primary route). Because routers prefer paths with lower administrative distance, the floating static route will only be installed into the routing table after the primary route fails and is removed.

Step-by-Step Solution

Evaluate the Administrative Distance requirement for backup routes.

Because OSPF has a default Administrative Distance (AD) of 110, a floating static route intended as a backup must be configured with an AD higher than 110 (such as 120).

Cisco IOS selects the route with the lowest AD value to place into the routing table.

Determine the condition under which the floating static route becomes active.

The floating static route remains inactive and out of the routing table until the primary OSPF route is lost or removed.

As long as the primary route with a lower AD exists in the routing table, higher-AD routes are kept in reserve.

Key Concept

Floating static routes use a higher Administrative Distance than the primary route protocol so they only enter the routing table when the primary route fails.

Question 13Question →

A network engineer inspects a router configuration designed to provide a redundant secondary path to a branch subnet $10.240.12.0/24$ . The primary path to this destination is dynamically learned via OSPF (default Administrative Distance of $110$ ). The engineer finds the following static route entry in the running configuration:

`ip route 10.240.12.0 255.255.255.0 192.168.1.2 95`

During normal operation with the OSPF link operational, traffic continues to traverse the backup link. Which TWO statements accurately explain this behavior and the required configuration fix?

Select all that apply

The configured static route takes precedence over the OSPF route because its configured administrative distance of

95

is lower than the OSPF default administrative distance of

110

Reconfiguring the static route with an administrative distance greater than

110

allows OSPF to act as the primary route while maintaining the static route as a floating backup.

The router load-balances traffic between OSPF and the static route because static routes automatically inherit the metric of active dynamic protocols.

Changing the static route's administrative distance to

90

will deactivate the static route and restore the OSPF path into the routing table.

Show answer & explanation

Answer: The configured static route takes precedence over the OSPF route because its configured administrative distance of $95$ is lower than the OSPF default administrative distance of $110$ .; Reconfiguring the static route with an administrative distance greater than $110$ allows OSPF to act as the primary route while maintaining the static route as a floating backup.

Answer

The static route currently pre-empts OSPF because its administrative distance (

95

) is lower than OSPF's default (

110

). To function correctly as a floating backup, the static route's administrative distance must be set to a value greater than

110

Cisco IOS routing table selection relies strictly on Administrative Distance (AD) when comparing routes learned from different sources for the exact same network prefix. OSPF has a default AD of

110

. The configured static route has an AD explicitly set to

95

. Because

95

is lower than

110

, the router prefers the static route, placing it into the routing table and routing all traffic across the backup link. To convert this into a functional floating static route, the AD of the static route must be increased to a value higher than

110

(for example,

120

), allowing OSPF to be preferred while the primary link is healthy.

Step-by-Step Solution

Analyze the Administrative Distance (AD) of the primary path protocol.

OSPF has a standard Cisco IOS default AD of

110

Routing decisions prioritize paths with the lowest administrative distance when identical prefix lengths are compared.

Evaluate the configured static route's AD.

The command `ip route 10.240.12.0 255.255.255.0 192.168.1.2 95` assigns an explicit AD of

95

Since

95 < 110

, the router installs the static route into the routing table as the active route, suppressing the OSPF route.

Determine the required administrative distance for a floating static route.

The static route's AD must be set higher than the primary path (

> 110

), such as

120

130

A floating static route remains out of the routing table until the primary lower-AD route is removed due to network topology changes or link failure.

Key Concept

Floating static routes rely on configuring an Administrative Distance higher than the primary dynamic routing protocol.

Estimated Time:2m 0s

Question 14Question →

An enterprise router displays the following output in its routing table:

text
Gateway of last resort is not set

10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
O 10.45.0.0/16 [110/20] via 192.168.1.1, 00:04:12, GigabitEthernet0/0

A network administrator needs to configure a backup floating static route to destination prefix $10.45.0.0/16$ via next-hop IP $192.168.2.1$ . The backup route must remain inactive in the routing table until the primary OSPF route becomes unavailable. Which command must be configured on the router to fulfill this requirement?

ip route 10.45.0.0 255.255.0.0 192.168.2.1 120

ip route 10.45.0.0 255.255.0.0 192.168.2.1 100

ip route 10.45.0.0 255.255.0.0 192.168.2.1

ip route 10.45.0.0 255.255.0.0 192.168.2.1 110

Show answer & explanation

Answer: ip route 10.45.0.0 255.255.0.0 192.168.2.1 120

Answer

The command 'ip route 10.45.0.0 255.255.0.0 192.168.2.1 120' correctly configures the floating static route.

The active route to network

10.45.0.0/16

is learned via OSPF, which has an Administrative Distance of 110. To create a floating static route that serves strictly as a backup, the static route must be configured with an Administrative Distance strictly greater than 110. Specifying a distance of 120 keeps the route out of the routing table while OSPF is functional, and allows Cisco IOS to automatically insert the static route if OSPF fails.

Step-by-Step Solution

Identify the Administrative Distance (AD) of the active primary route.

The routing table shows OSPF route [110/20], indicating a default Administrative Distance of

110

for OSPF.

Floating static routes rely on Administrative Distance comparison to determine installation eligibility in the routing table.

Determine the required Administrative Distance for a floating static backup route.

The backup static route must have an AD strictly greater than

110

(such as

120

Cisco IOS installs the route with the lowest Administrative Distance. Setting a higher AD keeps the static route floating in configuration without entering the active routing table until the primary route fails.

Formulate the correct Cisco IOS static route command syntax.

ip route 10.45.0.0 255.255.0.0 192.168.2.1 120

The trailing argument in the 'ip route' command defines the custom Administrative Distance.

Key Concept

Floating Static Route Administrative Distance Selection

Estimated Time:1m 30s

Question 15Question →

A network router currently receives its primary path to network 10.0.0.0/24 via RIP, which has a default administrative distance of 120. A network engineer needs to configure a static route to network 10.0.0.0/24 via the next-hop address 192.168.1.2 to act as a floating backup, activating only if the primary RIP route fails. Which command correctly configures this floating static route?

ip route 10.0.0.0 255.255.255.0 192.168.1.2 130

ip route 10.0.0.0 255.255.255.0 192.168.1.2

ip route 10.0.0.0 255.255.255.0 192.168.1.2 110

ip route 10.0.0.0 255.255.255.0 192.168.1.2 120

Show answer & explanation

Answer: ip route 10.0.0.0 255.255.255.0 192.168.1.2 130

Answer

ip route 10.0.0.0 255.255.255.0 192.168.1.2 130

The command 'ip route 10.0.0.0 255.255.255.0 192.168.1.2 130' assigns an administrative distance of 130 to the static route. Because 130 is greater than RIP's administrative distance of 120, Cisco IOS keeps the static route out of the routing table as long as the RIP route remains active. If the RIP route fails, the floating static route is inserted into the routing table as the backup path.

Step-by-Step Solution

Identify the primary routing protocol and its administrative distance.

The primary route is learned via RIP, which has a default administrative distance of 120.

Floating static routes rely on administrative distance values to determine route priority.

Determine the required administrative distance for a floating static route.

The administrative distance of the floating static route must be configured strictly greater than 120 (e.g., 130).

Cisco IOS prefers routes with lower administrative distances. To remain inactive in the routing table as a backup until the primary path disappears, the backup static route's administrative distance must be higher than that of the primary route.

Select the Cisco IOS command line syntax matching the required administrative distance.

The command 'ip route 10.0.0.0 255.255.255.0 192.168.1.2 130' correctly specifies a distance of 130.

Specifying 130 trailing the next-hop address correctly sets the administrative distance higher than RIP (120).

Key Concept

A floating static route requires an administrative distance configured higher than that of the active primary dynamic routing protocol.

Question 16Question →

Router R1 learns paths to remote subnet $192.168.100.0/24$ from two dynamic routing protocols: an Internal EIGRP path with an administrative distance of 90 and an OSPF path with an administrative distance of 110. An engineer must configure a floating static route pointing to next-hop $10.1.1.2$ that remains dormant in the routing table and only activates if both dynamic paths fail. Which command must be configured on R1?

ip route 192.168.100.0 255.255.255.0 10.1.1.2 115

ip route 192.168.100.0 255.255.255.0 10.1.1.2 95

ip route 192.168.100.0 255.255.255.0 10.1.1.2 1

ip route 192.168.100.0 255.255.255.0 10.1.1.2 90

Show answer & explanation

Answer: ip route 192.168.100.0 255.255.255.0 10.1.1.2 115

Answer

The command 'ip route 192.168.100.0 255.255.255.0 10.1.1.2 115' correctly configures the floating static route.

The correct command specifies an administrative distance of 115. Cisco IOS routers select routes for insertion into the routing table based on the lowest administrative distance. Because EIGRP has an AD of 90 and OSPF has an AD of 110, an AD value higher than 110 (such as 115) ensures the static route is ignored as long as either EIGRP or OSPF delivers a valid path. It will only be installed into the routing table as a floating backup when both dynamic routes are removed.

Step-by-Step Solution

Identify administrative distances of all active routing sources for destination 192.168.100.0/24

Internal EIGRP has AD = 90; OSPF has AD = 110.

Floating static routes rely on administrative distance values to dictate route installation hierarchy.

Determine the required administrative distance for the backup floating static route

The static route AD must be strictly greater than 110 (e.g., 115).

To ensure the static route activates only when BOTH dynamic paths (AD 90 and AD 110) are lost, its AD must exceed the highest AD of the active primary dynamic routes.

Select the command matching the syntax 'ip route <prefix> <mask> <next-hop> <distance>'

'ip route 192.168.100.0 255.255.255.0 10.1.1.2 115'

This command specifies destination 192.168.100.0/24 via next-hop 10.1.1.2 with an administrative distance of 115.

Key Concept

Floating Static Route Administrative Distance Selection

Question 17Question →

You are configuring a secondary gateway path on a corporate router for destination subnet 192.168.88.0/24 via next-hop IP address 10.5.5.2. The primary active route is learned dynamically via OSPF, which carries a default administrative distance of 110. What is the lowest administrative distance integer value that must be assigned at the end of the CLI command to ensure this static route functions as a floating backup route?

Fill in the blanks below

ip route 192.168.88.0 255.255.255.0 10.5.5.2

Show answer & explanation

Answer

111

A floating static route acts as a backup path and only enters the routing table when the primary routing path fails. Because Cisco routers prefer routes with lower administrative distance values, a floating static route must have an administrative distance higher than the primary route protocol. Since OSPF has a default administrative distance of 110, the lowest integer value that makes the static route floating is 111.

Step-by-Step Solution

Identify the administrative distance of the primary route.

The primary route is learned via OSPF, which has a default administrative distance of 110.

Cisco routers use administrative distance to rank route trustworthiness, preferring lower values.

Determine the minimum administrative distance required for a floating static backup route.

To ensure the static route remains inactive while OSPF is operational, its administrative distance must be strictly greater than 110.

The lowest integer greater than 110 is 111.

Key Concept

Floating Static Route Administrative Distance Selection

Estimated Time:45s

Question 18Question →

Complete the Cisco IOS command below to configure a floating static route for destination network $10.40.15.0/24$ using next-hop IP address $192.168.254.2$ to serve as a backup for a primary route learned via Internal EIGRP (Administrative Distance 90), specifying an administrative distance of $130$ .

Fill in the blanks below

Router(config)# ip route 10.40.15.0 255.255.255.0

Show answer & explanation

Answer

The completed Cisco IOS configuration command is `ip route 10.40.15.0 255.255.255.0 192.168.254.2 130`.

In Cisco IOS, the syntax for a static route is `ip route <prefix> <mask> <next-hop-ip> [administrative_distance]`. Specifying `192.168.254.2` as the next-hop IP address and appending `130` configures a floating static route. Because 130 is higher than Internal EIGRP's administrative distance of 90, the router keeps this static route inactive in the routing table until the primary EIGRP route is removed.

Step-by-Step Solution

Identify the target network prefix and network mask.

The target prefix is

10.40.15.0

and the subnet mask for

/24

255.255.255.0

Cisco IOS static route syntax requires the destination network prefix followed by its subnet mask.

Identify the next-hop IP address.

The next-hop IP address for the first blank is

192.168.254.2

Traffic destined for

10.40.15.0/24

over the backup link will be forwarded to this next-hop IP.

Determine the administrative distance value to make the static route floating.

The administrative distance for the second blank is

130

An administrative distance value greater than the primary routing protocol's AD (Internal EIGRP AD = 90) ensures the static route remains floating (inactive in the routing table) until the primary route fails.

Key Concept

Floating Static Route Configuration & Administrative Distance

Question 19Question →

An enterprise router receives its default route via an eBGP session established with ISP-A. A network administrator attempts to configure a secondary floating static backup default route pointing to ISP-B using the following command:

`ip route 0.0.0.0 0.0.0.0 198.51.100.2 15`

Assuming the eBGP session remains active and continues advertising the default route, which outcome will occur on the router?

The static route will immediately enter the routing table and replace the eBGP default route as the primary path.

The static route will remain inactive in the routing table until the primary eBGP neighbor session drops.

The router will perform equal-cost load balancing between the eBGP peer and the static route next-hop.

Cisco IOS will reject the command because administrative distance values below 20 are reserved for internal system protocols.

Show answer & explanation

Answer: The static route will immediately enter the routing table and replace the eBGP default route as the primary path.

Answer

The static route will immediately enter the routing table and replace the eBGP default route as the primary path.

In Cisco IOS, route selection between different protocol sources is determined by Administrative Distance (AD), where lower values are preferred. The default AD for External BGP (eBGP) is 20. Because the engineer configured the static route with an AD of 15, the router considers the static path more trustworthy than the eBGP path (

15 < 20

). Consequently, the static route immediately takes precedence in the routing table, failing to function as a floating backup.

Step-by-Step Solution

Identify the default administrative distance (AD) of the primary routing source.

External BGP (eBGP) has a default administrative distance of 20.

Cisco IOS assigns specific default AD values to judge route trustworthiness among different routing sources.

Compare the configured static route AD against the primary route's AD.

The configured static route AD is 15, which is lower than the eBGP AD of 20 (

15 < 20

Lower administrative distance values indicate higher trustworthiness in Cisco IOS forwarding selection logic.

Determine which route is installed into the routing table.

The static route with AD 15 overrides the eBGP route with AD 20 and is actively installed into the routing table.

To create a valid floating static backup, the backup route's AD must be strictly greater than the primary route's AD (e.g., AD > 20).

Key Concept

Floating Static Route Administrative Distance Requirements

Estimated Time:1m 30s

Question 20Question →

An enterprise router R1 learns the path to a remote branch subnet $10.150.0.0/16$ via Internal EIGRP, which has a default administrative distance of $90$ . A network engineer intends to configure a secondary floating static route via next-hop IP $192.168.99.2$ to serve strictly as a backup path when EIGRP fails. However, the engineer enters the following command on R1:

`ip route 10.150.0.0 255.255.0.0 192.168.99.2 85`

Which two statements correctly describe the operational impact of this configuration? (Select two.)

Select all that apply

The newly configured static route will immediately enter the Routing Information Base (RIB) and displace the EIGRP route as the active path.

To function correctly as a floating static backup route, the static route's administrative distance must be configured with a value greater than 90.

The static route will remain inactive in the routing table until the primary EIGRP neighbor adjacency fails, because dynamic routes take precedence over static routes by default.

Router R1 will perform equal-cost load balancing between the EIGRP path and the static route because both routes point to the same destination network.

Show answer & explanation

Answer: The newly configured static route will immediately enter the Routing Information Base (RIB) and displace the EIGRP route as the active path.; To function correctly as a floating static backup route, the static route's administrative distance must be configured with a value greater than 90.

Answer

The static route will immediately enter the routing table and displace the EIGRP route because its assigned administrative distance (85) is lower than Internal EIGRP (90). To act as a backup floating static route, its administrative distance must be set to a value greater than 90.

Cisco routers select routes from different routing sources based on Administrative Distance (AD), where lower AD values indicate higher preference. Internal EIGRP has a default AD of 90. Because the static route command explicitly defines an AD of 85, the static route is considered more trustworthy than EIGRP and is immediately placed into the routing table. To function properly as a floating static route, the static route must have an AD set higher than the primary route's AD (greater than 90) so it remains inactive until the primary EIGRP route vanishes.

Step-by-Step Solution

Identify the administrative distance of the primary route protocol.

Internal EIGRP has a default Administrative Distance (AD) of 90.

Administrative Distance defines the trustworthiness of a routing information source in Cisco IOS.

Analyze the configured static route's administrative distance parameter.

The command `ip route 10.150.0.0 255.255.0.0 192.168.99.2 85` explicitly assigns an AD of 85 to the static route.

The trailing numeric argument in the `ip route` syntax overrides the default static route AD of 1.

Compare administrative distances to determine routing table (RIB) selection.

Since

85 < 90

, the static route wins route selection over Internal EIGRP and is immediately installed into the RIB as the active route.

Lower AD values are strictly preferred over higher AD values.

Determine the necessary administrative distance for floating static functionality.

To float (remain inactive until the EIGRP path fails), the static route must be configured with an AD value strictly greater than 90 (e.g., 95, 130).

Floating static routes rely on a higher AD so they are suppressed while the lower-AD primary route is present in the routing table.

Key Concept

Floating Static Route Administrative Distance Selection

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