Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
Which statement best describes the benefit of PAT compared with static NAT in a small office that has many internal users but only one public IPv4 address?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Best answer
PAT lets many internal sessions share one public address using port numbers
This is correct because PAT scales outbound access by distinguishing sessions with ports.
B
Distractor review
PAT requires one public address for every internal host
This is wrong because that is the opposite of PAT’s main benefit.
C
Distractor review
PAT eliminates the need for a default route
This is wrong because PAT does not replace routing requirements.
D
Distractor review
PAT prevents any return traffic from reaching inside hosts
This is wrong because PAT supports correct return traffic for active sessions.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is selecting answers that confuse PAT with static NAT or misunderstand its function. For example, some may incorrectly believe PAT requires one public IP per internal host, which is the opposite of its purpose. Others might think PAT eliminates the need for routing or default routes, which it does not. Another common mistake is assuming PAT blocks return traffic; however, PAT maintains session state to allow return packets for active connections. Recognizing these misconceptions helps avoid incorrect choices and reinforces the correct understanding of PAT’s role in address translation and session multiplexing.
Technical deep dive
How to think about this question
Port Address Translation (PAT), also known as NAT overload, is a form of Network Address Translation that allows multiple internal hosts to share a single public IPv4 address by differentiating sessions using unique source port numbers. This technique enables many simultaneous outbound connections from a private network to the internet without requiring a unique public IP address for each device. PAT modifies both the IP address and the transport-layer port numbers in the packet headers to maintain session uniqueness. In a small office environment with many internal users but only one public IPv4 address, PAT is preferred over static NAT because static NAT requires a one-to-one mapping between internal and external IP addresses. Static NAT consumes public IP addresses inefficiently and does not scale well when the number of internal hosts exceeds available public IPs. PAT efficiently multiplexes multiple internal sessions through a single public IP by using port numbers, making it ideal for conserving scarce IPv4 addresses. A common exam trap is confusing PAT with static NAT or assuming PAT eliminates routing requirements. PAT does not remove the need for proper routing or default routes; it only translates addresses and ports. Another mistake is thinking PAT blocks return traffic; in reality, PAT maintains session state to allow return traffic for active connections. Understanding these distinctions is crucial for correctly answering NAT-related questions on the CCNA exam and for practical network design.
KKey Concepts to Remember
- PAT allows multiple internal hosts to share a single public IPv4 address by assigning unique source port numbers to each session.
- Static NAT requires a one-to-one mapping between internal and external IP addresses, consuming more public IP addresses than PAT.
- PAT maintains session state to permit return traffic for active connections, ensuring proper two-way communication.
- PAT does not eliminate the need for routing or default routes; it only translates IP addresses and port numbers.
- In small office networks with limited public IPv4 addresses, PAT efficiently scales outbound internet access for many users.
- Static NAT provides predictable address mappings but is inefficient for networks with many internal hosts and few public IPs.
- PAT distinguishes sessions by modifying transport-layer port numbers, enabling multiplexing of multiple connections over one IP.
- Understanding the difference between PAT and static NAT is critical for designing NAT solutions and answering CCNA exam questions.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Related practice questions
Related 200-301 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
CCNA subnetting practice questions
Practise IPv4 subnetting, CIDR, masks, host ranges and subnet selection.
CCNA OSPF practice questions
Practise OSPF neighbours, router IDs, metrics, areas and routing-table interpretation.
CCNA VLAN practice questions
Practise VLANs, access ports, trunks, allowed VLANs and switching scenarios.
CCNA STP practice questions
Practise spanning tree, root bridge election, port roles and STP troubleshooting.
CCNA EtherChannel practice questions
Practise LACP, PAgP, port-channel behaviour and bundle requirements.
CCNA ACL practice questions
Practise standard and extended ACLs, permit/deny logic and traffic filtering.
CCNA NAT practice questions
Practise static NAT, dynamic NAT, PAT and inside/outside address translation.
CCNA DHCP practice questions
Practise DHCP scopes, relay, leases and troubleshooting.
CCNA show ip route practice questions
Practise routing-table output, longest-prefix match, AD and route selection.
CCNA show interfaces trunk practice questions
Practise trunk verification and VLAN forwarding across switches.
CCNA wireless security practice questions
Practise WLAN security, authentication and wireless architecture concepts.
CCNA IPv6 practice questions
Practise IPv6 addressing, routes, neighbour discovery and common IPv6 exam traps.
More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
Question 2
A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?
Question 3
What is the OSPF metric called?
Question 4
A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?
Question 5
A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?
Question 6
A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?
FAQ
Questions learners often ask
What does this 200-301 question test?
PAT allows multiple internal hosts to share a single public IPv4 address by assigning unique source port numbers to each session.
What is the correct answer to this question?
The correct answer is: PAT lets many internal sessions share one public address using port numbers — PAT is more suitable because it lets many internal sessions share one public address by distinguishing them with transport-layer ports. In plain language, PAT allows a whole office to use one public IP for outbound access, while static NAT would require a separate permanent public mapping for each inside host or service. This question highlights the scaling difference between translation methods. Static NAT is predictable but address-hungry. PAT is efficient because it multiplexes many conversations through one address.
What should I do if I get this 200-301 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
Discussion
Loading comments…
Sign in to join the discussion.