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NAT with a pool 56 — two public addresses for Warangal
Enterprise Intermediate 3 devices 5 checked tasks 100 points Plan lab
Scenario — the provider gave Warangal a /29 (198.51.75.0/29, router side .1, provider .6) and two usable public addresses, .2 and .3. Translate the inside LAN 192.168.75.0/24 to a pool named PUBLIC with those two addresses (no overload), add a default route to the provider and ping the provider's test address 8.8.75.8. 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
the provider gave Warangal a /29 (198.51.75.0/29, router side .1, provider .6) and two usable public addresses, .2 and .3. Translate the inside LAN 192.168.75.0/24 to a pool named PUBLIC with those two addresses (no overload), add a default route to the provider and ping the provider's test address 8.8.75.8.
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 routers, 1 PC, cabled as drawn. No Layer 1 or Layer 2 faults: every link is connected and up. Edge-Warangal starts with addresses (G0/0 192.168.75.1/24, G0/1 198.51.75.1/29). ISP-Chandigarh starts with addresses (G0/1 198.51.75.6/29, L0 8.8.75.8/32). Inside-PC is a host with 192.168.75.10/24, gateway 192.168.75.1. 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
Gi0/0 is the inside and Gi0/1 the outside interface (20 pts) Pool PUBLIC holds 198.51.75.2 – 198.51.75.3 (25 pts) The inside LAN is translated through pool PUBLIC (20 pts) A default route points to the provider (10 pts) The inside PC reaches 8.8.75.8 (25 pts) The activity, in order
Gi0/0 is the inside and Gi0/1 the outside interface 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 Pool PUBLIC holds 198.51.75.2 – 198.51.75.3 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 inside LAN is translated through pool PUBLIC Why: A pool gives each inside host a public address of its own, for as long as the pool lasts. Verify with: show ip nat translations A default route points to the provider 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 The inside PC reaches 8.8.75.8 Why: A ping needs a route in BOTH directions. This is the end-to-end proof that everything before it worked. Verify with: ping 8.8.75.8 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: A pool netmask that disagrees with the provider subnet Common mistake: An ACL that does not match the inside subnet Common mistake: Forgetting the default route Why this matters
Dynamic NAT without overload gives each inside host its own public address from a pool, one-to-one, until the pool is empty. It is how a site with a handful of public addresses and a handful of hosts used to be built, and the pool size is the limit.
What you will be able to do
Define a NAT pool and an ACL
Bind them with ip nat inside source list … pool …
Explain why a pool runs out and overload does not
The network
ISR 2911, PC — 3 devices in all, already cabled.
Fa0 Gi0/0 192.168.75.1/24 Gi0/1 198.51.75.1/29 Gi0/1 198.51.75.6/29 Edge-Warangal ISP-Chandigarh Inside-PC 192.168.75.10/24 · gw 192.168.75.1 Drawn from this lab: devices, cables, ports and the addresses already set. Device Model Address already set
Edge-Warangal ISR 2911 configure it ISP-Chandigarh ISR 2911 configure it Inside-PC PC 192.168.75.10 / 255.255.255.0 gw 192.168.75.1
Cabling
Inside-PC Fa0 ↔ Edge-Warangal Gi0/0 Edge-Warangal Gi0/1 ↔ ISP-Chandigarh 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:
Edge-Warangal interface g0/0
ip address 192.168.75.1 255.255.255.0
no shutdown
exit
interface g0/1
ip address 198.51.75.1 255.255.255.248
no shutdown
exit ISP-Chandigarh interface g0/1
ip address 198.51.75.6 255.255.255.248
no shutdown
exit
interface lo0
ip address 8.8.75.8 255.255.255.255
no shutdown
exit 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 Gi0/0 is the inside and Gi0/1 the outside interface 20 On Edge-Warangal: show running-config contains the line(s) matching interface GigabitEthernet0/0 … ip nat inside. and On Edge-Warangal: show running-config contains the line(s) matching interface GigabitEthernet0/1 … ip nat outside. 2 Pool PUBLIC holds 198.51.75.2 – 198.51.75.3 25 On Edge-Warangal: show running-config contains the line(s) matching ip nat pool PUBLIC 198\.51\.75\.2 198\.51\.75\.3 netmask 255\.255\.255\.248. 3 The inside LAN is translated through pool PUBLIC 20 Checked automatically against the device’s live state (natPool). 4 A default route points to the provider 10 On Edge-Warangal: show ip route 0.0.0.0 shows next hop 198.51.75.6. 5 The inside PC reaches 8.8.75.8 25 On Inside-PC: ping 8.8.75.8 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
A pool netmask that disagrees with the provider subnet
An ACL that does not match the inside subnet
Forgetting the default route
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-Warangal access-list 1 permit 192.168.75.0 0.0.0.255
interface g0/0
ip nat inside
exit
interface g0/1
ip nat outside
exit
ip nat pool PUBLIC 198.51.75.2 198.51.75.3 netmask 255.255.255.248
ip nat inside source list 1 pool PUBLIC
ip route 0.0.0.0 0.0.0.0 198.51.75.6 Where this is examined
CCNA 4.0 NAT (dynamic NAT, pool vs PAT).
This lab practises these topics in the zNetLaB certification courses:
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