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Branch edge — NAT overload and an inbound ACL
Enterprise Intermediate 6 devices 5 checked tasks 100 points Plan lab
Translate the branch LAN behind one public address, then block one host from reaching the server. 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
Translate the branch LAN behind one public address, then block one host from reaching the server.
Your role: a network engineer on the enterprise team. Level: Intermediate Done when: all 5 goals show as passed (100 points).
Network status
Devices: 2 PCs, 1 switch, 2 routers, 1 server, cabled as drawn. No Layer 1 or Layer 2 faults: every link is connected and up. PC-A is a host with 192.168.10.10/24, gateway 192.168.10.1. PC-B is a host with 192.168.10.20/24, gateway 192.168.10.1. ISP starts with addresses (G0/0 198.51.100.1/30, G0/1 203.0.113.1/24) and static routes already configured. Web-Server is a host with 203.0.113.50/24, gateway 203.0.113.1. Branch-SW, Edge-RTR start with an empty configuration. 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
Edge inside g0/0 = 192.168.10.1/24, outside g0/1 = 198.51.100.2/30 (15 pts) A default route points at the ISP (10 pts) NAT inside/outside marked and overload configured (20 pts) PC-A reaches the web server (translated) (25 pts) An ACL blocks PC-B but still permits PC-A (30 pts) The activity, in order
Edge inside g0/0 = 192.168.10.1/24, outside g0/1 = 198.51.100.2/30 Why: A router interface routes nothing until it has an address and is up. Every other task builds on this one. Verify with: show ip interface brief A default route points at the ISP Why: The next hop must be an address on a directly connected subnet, or the route never enters the table. Verify with: show ip route NAT inside/outside marked and overload configured Why: NAT needs to know which side is inside; get it backwards and nothing translates. Verify with: show ip nat statistics PC-A reaches the web server (translated) Why: A ping needs a route in BOTH directions. This is the end-to-end proof that everything before it worked. Verify with: ping 203.0.113.50 An ACL blocks PC-B but still permits PC-A Why: A ping needs a route in BOTH directions. This is the end-to-end proof that everything before it worked. Verify with: ping 203.0.113.50 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. Why this matters
Translate the branch LAN behind one public address, then block one host from reaching the server.
What you will be able to do
Edge inside g0/0 = 192.168.10.1/24, outside g0/1 = 198.51.100.2/30
A default route points at the ISP
NAT inside/outside marked and overload configured
PC-A reaches the web server (translated)
The network
PC, Switch 8-port, ISR 2911, Server — 6 devices in all, already cabled.
Fa0 Fa0/1 Fa0 Fa0/2 Fa0/3 Gi0/0 Gi0/1 Gi0/0 198.51.100.1/30 Gi0/1 203.0.113.1/24 Fa0 PC-A 192.168.10.10/24 · gw 192.168.10.1 PC-B 192.168.10.20/24 · gw 192.168.10.1 Branch-SW Edge-RTR ISP Web-Server 203.0.113.50/24 · gw 203.0.113.1 Drawn from this lab: devices, cables, ports and the addresses already set. Device Model Address already set
PC-A PC 192.168.10.10 / 255.255.255.0 gw 192.168.10.1 PC-B PC 192.168.10.20 / 255.255.255.0 gw 192.168.10.1 Branch-SW Switch 8-port configure it Edge-RTR ISR 2911 configure it ISP ISR 2911 configure it Web-Server Server 203.0.113.50 / 255.255.255.0 gw 203.0.113.1
Cabling
PC-A Fa0 ↔ Branch-SW Fa0/1 PC-B Fa0 ↔ Branch-SW Fa0/2 Branch-SW Fa0/3 ↔ Edge-RTR Gi0/0 Edge-RTR Gi0/1 ↔ ISP Gi0/0 ISP Gi0/1 ↔ Web-Server Fa0
What is configured at the start
These are already configured when the lab opens — including, where this is a troubleshooting lab, the fault itself:
ISP interface g0/0
ip address 198.51.100.1 255.255.255.252
no shutdown
exit
interface g0/1
ip address 203.0.113.1 255.255.255.0
no shutdown
exit
ip route 0.0.0.0 0.0.0.0 198.51.100.2 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 Edge inside g0/0 = 192.168.10.1/24, outside g0/1 = 198.51.100.2/30 15 On Edge-RTR: show ip interface brief — Gi0/0 has 192.168.10.1 and is up/up. and On Edge-RTR: show ip interface brief — Gi0/1 has 198.51.100.2 and is up/up. 2 A default route points at the ISP 10 On Edge-RTR: show ip route 0.0.0.0 shows next hop 198.51.100.1. 3 NAT inside/outside marked and overload configured 20 On Edge-RTR: show ip nat statistics — Gi0/0 is inside. and On Edge-RTR: show ip nat statistics — Gi0/1 is outside. and On Edge-RTR: show running-config | include nat shows overload . 4 PC-A reaches the web server (translated) 25 On PC-A: ping 203.0.113.50 must succeed. 5 An ACL blocks PC-B but still permits PC-A 30 On PC-A: ping 203.0.113.50 must succeed. and On PC-B: ping 203.0.113.50 must fail — the policy blocks it.
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
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:
Edge-RTR interface g0/0
ip address 192.168.10.1 255.255.255.0
ip nat inside
no shutdown
exit
interface g0/1
ip address 198.51.100.2 255.255.255.252
ip nat outside
no shutdown
exit
ip route 0.0.0.0 0.0.0.0 198.51.100.1
access-list 1 permit 192.168.10.0 0.0.0.255
ip nat inside source list 1 interface g0/1 overload
access-list 110 deny ip host 192.168.10.20 any
access-list 110 permit ip any any
interface g0/0
ip access-group 110 in Where this is examined
This lab practises these topics in the zNetLaB certification courses:
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