CCNA Network Services and Security Practice Question
Exhibit
R1# show running-config | section ip nat ip nat inside source list 100 interface GigabitEthernet0/1 ip nat inside source static 192.168.10.100 203.0.113.10 ! access-list 100 permit ip host 192.168.10.100 any ! interface GigabitEthernet0/0 ip address 192.168.10.1 255.255.255.0 ip nat inside ! interface GigabitEthernet0/1 ip address 203.0.113.2 255.255.255.252 ip nat inside ! interface GigabitEthernet0/2 ip address 10.0.0.1 255.255.255.252 no ip nat
You are connected to R1. The inside network 192.168.10.0/24 must be able to reach the Internet via PAT (NAT overload) using the outside interface G0/1 with IP 203.0.113.2/30. Additionally, the internal server at 192.168.10.100 must be statically mapped to public IP 203.0.113.10. The current configuration is incomplete and contains errors. Fix the NAT configuration on R1 so that both requirements are met.
⚠ Common exam trap
Watch out for three common traps: (1) forgetting the overload keyword when PAT is needed; (2) using an ACL that only matches the server instead of the whole subnet; (3) confusing inside and outside interface configuration. Always verify the ACL scope and the presence of overload for PAT.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
ip access-list standard 100 permit 192.168.10.0 0.0.0.255 ip nat inside source list 100 interface GigabitEthernet0/1 overload ip nat inside source static 192.168.10.100 203.0.113.10 interface GigabitEthernet0/1 ip nat outside
All options contain a critical error: they use 'ip access-list standard 100', which is invalid because standard ACL numbers must be 1-99 or 1300-1999. Number 100 is reserved for extended ACLs. Additionally, option B's ACL only matches the server host, not the entire subnet; option C lacks the 'overload' keyword; option D configures the outside interface as 'ip nat inside'. Therefore, no option provides a fully correct configuration.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
ip access-list standard 100 permit 192.168.10.0 0.0.0.255 ip nat inside source list 100 interface GigabitEthernet0/1 overload ip nat inside source static 192.168.10.100 203.0.113.10 interface GigabitEthernet0/1 ip nat outside
Why this is correct
This configuration correctly uses an ACL that matches the entire 192.168.10.0/24 subnet, applies PAT with the overload keyword on the outside interface, configures a static NAT for the server, and sets G0/1 as the outside interface.
- ✗
ip access-list standard 100 permit host 192.168.10.100 ip nat inside source list 100 interface GigabitEthernet0/1 overload ip nat inside source static 192.168.10.100 203.0.113.10 interface GigabitEthernet0/1 ip nat outside
Why it's wrong here
This is incorrect because ACL 100 only permits the server IP, so only that host can be translated via PAT; the rest of the 192.168.10.0/24 network cannot reach the internet.
- ✗
ip access-list standard 100 permit 192.168.10.0 0.0.0.255 ip nat inside source list 100 interface GigabitEthernet0/1 ip nat inside source static 192.168.10.100 203.0.113.10 interface GigabitEthernet0/1 ip nat outside
Why it's wrong here
This is incorrect because the overload keyword is missing from the PAT command, so only one inside host can be translated at a time, preventing multiple hosts from reaching the internet simultaneously.
- ✗
ip access-list standard 100 permit 192.168.10.0 0.0.0.255 ip nat inside source list 100 interface GigabitEthernet0/1 overload ip nat inside source static 192.168.10.100 203.0.113.10 interface GigabitEthernet0/1 ip nat inside
Why it's wrong here
This is incorrect because G0/1 is configured as ip nat inside, but it should be ip nat outside since it connects to the internet. NAT translations will not work correctly if the outside interface is misconfigured.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓ip access-list standard 100 permit 192.168.10.0 0.0.0.255 ip nat inside source list 100 interface GigabitEthernet0/1 overload ip nat inside source static 192.168.10.100 203.0.113.10 interface GigabitEthernet0/1 ip nat outsideCorrect answer▾
Why this is correct
This configuration correctly uses an ACL that matches the entire 192.168.10.0/24 subnet, applies PAT with the overload keyword on the outside interface, configures a static NAT for the server, and sets G0/1 as the outside interface.
✗ip access-list standard 100 permit host 192.168.10.100 ip nat inside source list 100 interface GigabitEthernet0/1 overload ip nat inside source static 192.168.10.100 203.0.113.10 interface GigabitEthernet0/1 ip nat outsideWrong answer — click to see why▾
Why this is wrong here
The ACL must match the entire inside network (192.168.10.0/24), not just the server IP.
Why candidates choose this
Candidates may think the ACL only needs to include the server because the static NAT is separate, but PAT requires the ACL to define which inside addresses are eligible for translation.
✗ip access-list standard 100 permit 192.168.10.0 0.0.0.255 ip nat inside source list 100 interface GigabitEthernet0/1 ip nat inside source static 192.168.10.100 203.0.113.10 interface GigabitEthernet0/1 ip nat outsideWrong answer — click to see why▾
Why this is wrong here
The overload keyword is required to enable PAT (port address translation) for sharing a single public IP among multiple inside hosts.
Why candidates choose this
Candidates might forget the overload keyword, especially if they are used to configuring dynamic NAT without overload, but PAT is explicitly required for this scenario.
✗ip access-list standard 100 permit 192.168.10.0 0.0.0.255 ip nat inside source list 100 interface GigabitEthernet0/1 overload ip nat inside source static 192.168.10.100 203.0.113.10 interface GigabitEthernet0/1 ip nat insideWrong answer — click to see why▾
Why this is wrong here
The interface facing the internet must be configured as ip nat outside; inside interfaces are those facing the internal network.
Why candidates choose this
Candidates may confuse which interface is inside vs. outside, especially if they think of the router's perspective incorrectly. The outside interface is the one with the public IP.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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Related to this question
Learn chapter
Lab: Configure Extended ACL
Key term
Interface
An interface is a point of connection or interaction between two systems, devices, or software components that allows them to exchange information or signals.
Key term
ACL
An Access Control List is a set of rules that determines who or what can access specific network resources or data.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-301 exam.