zNetLaB › Guided labs › Enterprise
Administrative distance — a backup route that must not win
Enterprise Intermediate 2 devices 3 checked tasks 100 points Plan lab
OSPF carries the route (distance 110). A static route to the same network is also configured as a safety net. With the default distance of 1 the static route would silently override OSPF; set its distance above 110 so OSPF is used until it fails — and prove which source is in the table. You build it in a browser, type real commands at each device, and every task below is
checked against the running configuration — so you find out it is wrong before anybody else does.
Open this lab in the simulator
The simulator runs in your browser with nothing to install. This lab is part of the full simulator: open it free for 7 days with a new account, then with a plan. It needs an account, which keeps your progress.
The scenario
OSPF carries the route (distance 110). A static route to the same network is also configured as a safety net. With the default distance of 1 the static route would silently override OSPF; set its distance above 110 so OSPF is used until it fails — and prove which source is in the table.
Your role: a network engineer on the enterprise team. Level: Intermediate Done when: all 3 goals show as passed (100 points).
Network status
Devices: 2 routers, cabled as drawn. No Layer 1 or Layer 2 faults: every link is connected and up. R1 starts with addresses (G0/1 10.0.12.1/30) and OSPF 1 already configured. R2 starts with addresses (G0/1 10.0.12.2/30, L9 172.20.0.1/24) and OSPF 1 already configured. Known problems
None: nothing is misconfigured. The network is simply not finished: what the goals list is what you have to build or secure. Goals
R1 has a static route to 172.20.0.0/24 as a backup, with a distance above OSPF’s 110 (40 pts) The route in the table is the OSPF one, not the static (40 pts) R1 reaches the far loopback (20 pts) The activity, in order
R1 has a static route to 172.20.0.0/24 as a backup, with a distance above OSPF’s 110 Why: This is the task that checks your configuration directly: the line must really be there, not just look right. Verify with: show running-config The route in the table is the OSPF one, not the static Why: Reading a show command is the core skill of troubleshooting: the output is the truth, not your configuration. Verify with: show ip route 172.20.0.0 R1 reaches the far loopback Why: A ping needs a route in BOTH directions. This is the end-to-end proof that everything before it worked. Verify with: ping 172.20.0.1 Tips
Work in the order given: later goals depend on the earlier ones. After every change, run the verify command before moving on; do not guess. Stuck? Read the verify output first. It names the interface, neighbour or route that is wrong. Common mistake: Confusing distance with metric Common mistake: A backup distance lower than the primary Common mistake: Expecting the backup to be visible in the table Why this matters
When two sources offer the same prefix, administrative distance picks the source: lower wins. A static route with the default distance of 1 silently overrides OSPF’s 110; a “floating” static above 110 is only a backup.
What you will be able to do
State the default distances of common sources
Configure a floating static route
Prove which route is in the table
The network
ISR 2911 — 2 devices in all, already cabled.
Gi0/1 10.0.12.1/30 Gi0/1 10.0.12.2/30 R1 R2 Drawn from this lab: devices, cables, ports and the addresses already set. Device Model Address already set
R1 ISR 2911 configure it R2 ISR 2911 configure it
Cabling
R1 Gi0/1 ↔ R2 Gi0/1
What is configured at the start
These are already configured when the lab opens — including, where this is a troubleshooting lab, the fault itself:
R1 interface g0/1
ip address 10.0.12.1 255.255.255.252
no shutdown
exit
router ospf 1
router-id 1.1.1.1
network 10.0.12.0 0.0.0.3 area 0 R2 interface g0/1
ip address 10.0.12.2 255.255.255.252
no shutdown
exit
interface lo9
ip address 172.20.0.1 255.255.255.0
no shutdown
exit
router ospf 1
router-id 2.2.2.2
network 10.0.12.0 0.0.0.3 area 0
network 172.20.0.0 0.0.0.255 area 0 Tasks, and how each one is checked
Every task is decided by reading the live network — a neighbour in FULL, a ping that succeeds, a line in the running configuration — not by looking for a keyword you typed. The same command shows you what the lab sees.
# Task Pts How to verify it yourself
1 R1 has a static route to 172.20.0.0/24 as a backup, with a distance above OSPF’s 110 40 On R1: show running-config contains the line(s) matching ip route 172\.20\.0\.0 255\.255\.255\.0 10\.0\.12\.2 (1[1-9][0-9]|2[0-9][0-9]). 2 The route in the table is the OSPF one, not the static 40 On R1: show ip route 172.20.0.0 output matches Known via "ospf. 3 R1 reaches the far loopback 20 On R1: ping 172.20.0.1 must succeed.
Stuck? Ask the coach
Tell the coach what you see or what you tried. It gives you a hint, not the answer, the way a senior engineer would. Included with a free trial or any plan.
Ask the coach
Common mistakes
Confusing distance with metric
A backup distance lower than the primary
Expecting the backup to be visible in the table
Reference solution
Try it yourself first — the lab checks your work either way. This is one configuration that makes every task pass, device by device:
R1 ip route 172.20.0.0 255.255.255.0 10.0.12.2 150 Where this is examined
CCNA (routing table), CCNP ENCOR (route selection), Network+.
This lab practises these topics in the zNetLaB certification courses:
Related labs
Where to start
The lessons all guided labs plans
CCNA®, CCNP® and Cisco® are trademarks of Cisco Systems, Inc. zNetLaB is not affiliated with or endorsed by Cisco.