The correct configuration requires three specific fixes: change GigabitEthernet0/1 to `ip nat outside`, add the `overload` keyword to the PAT command, and update access-list 1 to permit `192.168.1.0 0.0.0.255`. This works because PAT overload translates multiple inside hosts to a single outside interface IP by tracking port numbers, while static NAT creates a permanent one-to-one mapping for a specific host. On the CCNA 200-301 v2 exam, this question tests your ability to distinguish between inside and outside interface roles, recognize that PAT requires the `overload` keyword to enable port address translation, and verify that the ACL matches the correct inside network. A common trap is confusing the ACL’s permit statement with the inside network range—many candidates leave the default or wrong subnet in place. Remember the memory tip: “Outside interface, overload keyword, correct ACL network” to catch all three errors at once.
CCNA Network Services and Security Practice Question
This 200-301 practice question tests your understanding of network services and security. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Network Topology
You are connected to R1. The inside network 192.168.1.0/24 must be translated to the outside interface IP (198.51.100.1) using PAT (NAT overload). Additionally, a static NAT entry must map host 192.168.1.10 to 203.0.113.10. The current configuration is incomplete and contains errors. Correct the configuration so that both translations work properly.
R1# show running-config | section ip nat
ip nat inside source list 1 interface GigabitEthernet0/1
ip nat inside source static 192.168.1.10 203.0.113.10
!
interface GigabitEthernet0/0
ip address 192.168.1.1 255.255.255.0
ip nat inside
!
interface GigabitEthernet0/1
ip address 198.51.100.1 255.255.255.0
ip nat inside
!
access-list 1 permit 10.0.0.0 0.255.255.255
A
interface GigabitEthernet0/1
ip nat outside
!
access-list 1 permit 192.168.1.0 0.0.0.255
!
ip nat inside source list 1 interface GigabitEthernet0/1 overload
ip nat inside source static 192.168.1.10 203.0.113.10
This configuration correctly sets GigabitEthernet0/1 as the outside interface, uses an ACL that matches the inside network 192.168.1.0/24, includes the 'overload' keyword for PAT, and adds the static NAT entry for host 192.168.1.10.
B
interface GigabitEthernet0/1
ip nat inside
!
access-list 1 permit 192.168.1.0 0.0.0.255
!
ip nat inside source list 1 interface GigabitEthernet0/1 overload
ip nat inside source static 192.168.1.10 203.0.113.10
Why wrong: This is incorrect because GigabitEthernet0/1 is set as 'ip nat inside' instead of 'ip nat outside'. The outside interface must be marked as 'ip nat outside' for NAT to function correctly.
C
interface GigabitEthernet0/1
ip nat outside
!
access-list 1 permit 10.0.0.0 0.255.255.255
!
ip nat inside source list 1 interface GigabitEthernet0/1
ip nat inside source static 192.168.1.10 203.0.113.10
Why wrong: This is incorrect because the ACL permits 10.0.0.0/8 instead of 192.168.1.0/24, and the PAT command is missing the 'overload' keyword. Without 'overload', only one translation can occur at a time.
D
interface GigabitEthernet0/1
ip nat outside
!
access-list 1 permit 192.168.1.0 0.0.0.255
!
ip nat inside source list 1 interface GigabitEthernet0/1 overload
ip nat inside source static tcp 192.168.1.10 80 203.0.113.10 80
Why wrong: This is incorrect because the static NAT entry specifies a TCP port, which would only translate traffic for that specific port and protocol, not all traffic for host 192.168.1.10. The requirement is for a full static NAT mapping.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
interface GigabitEthernet0/1
ip nat outside
!
access-list 1 permit 192.168.1.0 0.0.0.255
!
ip nat inside source list 1 interface GigabitEthernet0/1 overload
ip nat inside source static 192.168.1.10 203.0.113.10
The configuration has three issues: 1) GigabitEthernet0/1 is incorrectly set as 'ip nat inside' instead of 'ip nat outside'. 2) The PAT command is missing the 'overload' keyword. 3) Access-list 1 permits 10.0.0.0/8, not the inside subnet 192.168.1.0/24. The commands fix these: change the interface to 'ip nat outside', add 'overload' to the PAT command, and update the ACL to permit the correct inside network.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
interface GigabitEthernet0/1
ip nat outside
!
access-list 1 permit 192.168.1.0 0.0.0.255
!
ip nat inside source list 1 interface GigabitEthernet0/1 overload
ip nat inside source static 192.168.1.10 203.0.113.10
Why this is correct
This configuration correctly sets GigabitEthernet0/1 as the outside interface, uses an ACL that matches the inside network 192.168.1.0/24, includes the 'overload' keyword for PAT, and adds the static NAT entry for host 192.168.1.10.
interface GigabitEthernet0/1
ip nat inside
!
access-list 1 permit 192.168.1.0 0.0.0.255
!
ip nat inside source list 1 interface GigabitEthernet0/1 overload
ip nat inside source static 192.168.1.10 203.0.113.10
Why it's wrong here
This is incorrect because GigabitEthernet0/1 is set as 'ip nat inside' instead of 'ip nat outside'. The outside interface must be marked as 'ip nat outside' for NAT to function correctly.
✗
interface GigabitEthernet0/1
ip nat outside
!
access-list 1 permit 10.0.0.0 0.255.255.255
!
ip nat inside source list 1 interface GigabitEthernet0/1
ip nat inside source static 192.168.1.10 203.0.113.10
Why it's wrong here
This is incorrect because the ACL permits 10.0.0.0/8 instead of 192.168.1.0/24, and the PAT command is missing the 'overload' keyword. Without 'overload', only one translation can occur at a time.
✗
interface GigabitEthernet0/1
ip nat outside
!
access-list 1 permit 192.168.1.0 0.0.0.255
!
ip nat inside source list 1 interface GigabitEthernet0/1 overload
ip nat inside source static tcp 192.168.1.10 80 203.0.113.10 80
Why it's wrong here
This is incorrect because the static NAT entry specifies a TCP port, which would only translate traffic for that specific port and protocol, not all traffic for host 192.168.1.10. The requirement is for a full static NAT mapping.
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.
✓interface GigabitEthernet0/1
ip nat outside
!
access-list 1 permit 192.168.1.0 0.0.0.255
!
ip nat inside source list 1 interface GigabitEthernet0/1 overload
ip nat inside source static 192.168.1.10 203.0.113.10Correct answer▾
Why this is correct
This configuration correctly sets GigabitEthernet0/1 as the outside interface, uses an ACL that matches the inside network 192.168.1.0/24, includes the 'overload' keyword for PAT, and adds the static NAT entry for host 192.168.1.10.
✗interface GigabitEthernet0/1
ip nat inside
!
access-list 1 permit 192.168.1.0 0.0.0.255
!
ip nat inside source list 1 interface GigabitEthernet0/1 overload
ip nat inside source static 192.168.1.10 203.0.113.10Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the interface facing the outside (public) network is incorrectly configured as 'ip nat inside'.
Why candidates choose this
Candidates might think that both inside and outside interfaces can be marked as 'inside' if they are internal, but the outside interface must be explicitly marked as 'outside'.
✗interface GigabitEthernet0/1
ip nat outside
!
access-list 1 permit 10.0.0.0 0.255.255.255
!
ip nat inside source list 1 interface GigabitEthernet0/1
ip nat inside source static 192.168.1.10 203.0.113.10Wrong answer — click to see why▾
Why this is wrong here
The specific factual errors are: 1) The ACL does not match the correct inside network. 2) The 'overload' keyword is omitted, preventing PAT from working.
Why candidates choose this
Candidates might mistakenly use a standard ACL that permits a different private range (10.0.0.0/8) and forget the 'overload' keyword, thinking it is optional.
✗interface GigabitEthernet0/1
ip nat outside
!
access-list 1 permit 192.168.1.0 0.0.0.255
!
ip nat inside source list 1 interface GigabitEthernet0/1 overload
ip nat inside source static tcp 192.168.1.10 80 203.0.113.10 80Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the static NAT command includes protocol and port, limiting the translation to TCP port 80 only.
Why candidates choose this
Candidates might think that static NAT requires specifying a port for the translation, but a simple 'ip nat inside source static' without port creates a one-to-one mapping for all traffic.
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?”
Common exam traps
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Trap categories for this question
Keyword trap
This is incorrect because the ACL permits 10.0.0.0/8 instead of 192.168.1.0/24, and the PAT command is missing the 'overload' keyword. Without 'overload', only one translation can occur at a time.
Command / output trap
This is incorrect because the ACL permits 10.0.0.0/8 instead of 192.168.1.0/24, and the PAT command is missing the 'overload' keyword. Without 'overload', only one translation can occur at a time.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.
TExam Day Tips
→Write the block size before choosing the subnet.
→Check whether the question asks for hosts, subnets or a specific address range.
→Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 200-301 question in full detail.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related 200-301 subnetting questions on CIDR, address ranges, and subnet selection.
Network Services and Security — This question tests Network Services and Security — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: interface GigabitEthernet0/1
ip nat outside
!
access-list 1 permit 192.168.1.0 0.0.0.255
!
ip nat inside source list 1 interface GigabitEthernet0/1 overload
ip nat inside source static 192.168.1.10 203.0.113.10 — The configuration has three issues: 1) GigabitEthernet0/1 is incorrectly set as 'ip nat inside' instead of 'ip nat outside'. 2) The PAT command is missing the 'overload' keyword. 3) Access-list 1 permits 10.0.0.0/8, not the inside subnet 192.168.1.0/24. The commands fix these: change the interface to 'ip nat outside', add 'overload' to the PAT command, and update the ACL to permit the correct inside network.
What should I do if I get this 200-301 question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related 200-301 subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
About these practice questions
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These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. You are connected to R1. The network uses 192.168.1.0/24 for internal hosts and 203.0.113.0/29 for the public IP pool (203.0.113.2 is the outside interface). Configure PAT so that inside hosts can reach the Internet using the pool address 203.0.113.2. Also configure static NAT to map internal server 192.168.1.10 to 203.0.113.3. The initial config has errors; identify and fix them.
hard
✓ A.Change ACL 10 to permit 192.168.1.0 0.0.0.255 and ensure the NAT pool and PAT are correctly configured.
B.Change the NAT pool to use a different public IP address and update the static NAT mapping.
C.Remove the static NAT and use PAT for the server as well.
D.Change the inside interface IP address to match the ACL.
Why A: The ACL 10 permits 10.0.0.0/8, but inside hosts are on 192.168.1.0/24 — this ACL does not match the inside subnet, so PAT fails. The static NAT is correct. To fix: change ACL 10 to permit 192.168.1.0 0.0.0.255. Also ensure the PAT references the correct ACL; currently it uses list 10, so after fixing the ACL, PAT will work. No other changes needed.
Variation 2. You are connected to R1. The network uses private IP 10.10.10.0/24 on the inside and must reach the Internet via the outside interface G0/1 with public IP 203.0.113.1/29. Configure PAT (NAT overload) so that inside hosts can access the Internet, and also configure a static NAT for the internal server 10.10.10.100 to public IP 203.0.113.2. The current configuration has errors: the inside and outside interfaces are swapped, the ACL is incorrectly defined, and the overload keyword is missing. Fix all issues.
hard
✓ A.On G0/0: ip nat inside; on G0/1: ip nat outside; ACL 10 permit 10.10.10.0 0.0.0.255; ip nat inside source list 10 interface GigabitEthernet0/1 overload
B.On G0/0: ip nat outside; on G0/1: ip nat inside; ACL 10 permit 10.10.10.0 0.0.0.255; ip nat inside source list 10 interface GigabitEthernet0/1 overload
C.On G0/0: ip nat inside; on G0/1: ip nat outside; ACL 10 permit 192.168.1.0 0.0.0.255; ip nat inside source list 10 interface GigabitEthernet0/1 overload
D.On G0/0: ip nat inside; on G0/1: ip nat outside; ACL 10 permit 10.10.10.0 0.0.0.255; ip nat inside source list 10 interface GigabitEthernet0/1
Why A: The configuration had three faults: (1) The inside interface (G0/0 with private IP) was marked 'ip nat outside', and the outside interface (G0/1 with public IP) was marked 'ip nat inside' — these must be swapped. (2) The ACL 10 permitted 192.168.1.0/24 instead of the actual inside subnet 10.10.10.0/24. (3) The NAT command 'ip nat inside source list 10 interface GigabitEthernet0/1' was missing the 'overload' keyword, which is required for PAT. The static NAT was correctly defined. After fixing all three, inside hosts will be able to access the Internet using PAT.
Last reviewed: Jun 6, 2026
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