CCNA NAT Overload (PAT) Practice Question
Exhibit
ip nat inside source list 10 interface g0/0 overload access-list 10 permit 192.168.10.0 0.0.0.255 ! interface g0/0 ip address 203.0.113.2 255.255.255.252 ! interface g0/1 ip address 192.168.10.1 255.255.255.0 ip nat inside
A router is configured for NAT overload, but translations never appear when inside users browse the internet. Which issue is most likely?
⚠ Common exam trap
Ensure inside and outside interfaces are correctly set for NAT; misconfigurations here are a common oversight.
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
✓
The outside interface is missing the ip nat outside command
NAT needs the inside and outside interfaces marked correctly. If those roles are missing or reversed, the router has no context for translating traffic and the NAT table stays empty.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The outside interface is missing the ip nat outside command
Why this is correct
Without inside and outside roles, overload translations will not build correctly.
- ✗
The ACL used by NAT must deny inside addresses
Why it's wrong here
The NAT ACL should usually match the inside local addresses to be translated.
When this WOULD be correct
If the question were about restricting NAT to only certain inside hosts (e.g., 'Which ACL configuration would prevent inside users from being translated?'), then an ACL that denies those addresses would be correct.
- ✗
PAT requires DHCP on the inside interface
Why it's wrong here
PAT does not require DHCP.
When this WOULD be correct
If the question asked 'Which feature is required on the inside interface for NAT overload to translate private addresses when using dynamic addressing?', then DHCP would be correct because inside hosts need IP addresses from a DHCP server to communicate through NAT.
- ✗
NAT overload works only with OSPF-learned routes
Why it's wrong here
NAT is independent of the routing protocol choice.
When this WOULD be correct
In a scenario where the question specifies that NAT overload must only translate traffic for routes learned via OSPF (e.g., to restrict translation to specific destinations), then an ACL or route-map referencing OSPF-learned routes could be required. For example: 'A router must perform NAT overload only for traffic destined to networks learned via OSPF. Which configuration is needed?'
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.
✓The outside interface is missing the ip nat outside commandCorrect answer▾
Why this is correct
Without inside and outside roles, overload translations will not build correctly.
✗The ACL used by NAT must deny inside addressesWrong answer — click to see why▾
Why this is wrong here
The ACL used by NAT should match the inside local addresses that need to be translated, typically using a permit statement. If the ACL denies inside addresses, no traffic will be matched for translation, causing NAT to fail. The correct ACL should permit the inside network.
★ When this WOULD be the correct answer
If the question were about restricting NAT to only certain inside hosts (e.g., 'Which ACL configuration would prevent inside users from being translated?'), then an ACL that denies those addresses would be correct.
Why candidates choose this
Students might think that NAT should deny private addresses to prevent them from being translated, but in reality, NAT translates private addresses to public ones. The confusion arises from the idea of filtering traffic, but NAT ACLs are used to identify which addresses to translate, not to block them.
✗PAT requires DHCP on the inside interfaceWrong answer — click to see why▾
Why this is wrong here
PAT (Port Address Translation) does not require DHCP on any interface. PAT translates multiple private IP addresses to a single public IP using different port numbers, and it works independently of how IP addresses are assigned. DHCP is only needed if the interface needs to obtain an IP address dynamically.
★ When this WOULD be the correct answer
If the question asked 'Which feature is required on the inside interface for NAT overload to translate private addresses when using dynamic addressing?', then DHCP would be correct because inside hosts need IP addresses from a DHCP server to communicate through NAT.
Why candidates choose this
Some students may associate NAT with DHCP because both are often used together in home networks to provide internet access. However, they are separate functions; DHCP assigns IP addresses, while NAT translates them. PAT can work with static IPs or DHCP-assigned IPs.
✗NAT overload works only with OSPF-learned routesWrong answer — click to see why▾
Why this is wrong here
NAT overload (PAT) is independent of the routing protocol used. It works with static routes, OSPF, EIGRP, or any other routing protocol. The routing protocol only affects how packets are forwarded, not how NAT translates addresses.
★ When this WOULD be the correct answer
In a scenario where the question specifies that NAT overload must only translate traffic for routes learned via OSPF (e.g., to restrict translation to specific destinations), then an ACL or route-map referencing OSPF-learned routes could be required. For example: 'A router must perform NAT overload only for traffic destined to networks learned via OSPF. Which configuration is needed?'
Why candidates choose this
Students might think that because OSPF is a common protocol in enterprise networks, NAT might depend on it. However, NAT operates at Layer 3 and is not tied to any specific routing protocol. The confusion may come from the fact that NAT often works with routing to ensure return traffic reaches the correct inside host.
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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Key term
Port Address Translation
A networking technique that maps multiple private IP addresses and their ports to a single public IP address using unique port numbers.
Key term
NAT overload
NAT overload is a form of network address translation that allows many devices on a private network to share a single public IP address by using unique port numbers to track each connection.
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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.