Question 1hardmulti select
Full question →hardmulti selectObjective-mapped
Which two statements accurately compare IPv4 private addresses and public addresses?
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
Private IPv4 addresses are not directly Internet-routable.
This is correct because RFC 1918 private ranges are intended for internal use and are not routed on the public Internet.
B
Best answer
Public IPv4 addresses are intended to be globally unique and routable.
This is correct because public IPv4 addresses are used for global Internet reachability.
C
Distractor review
Private IPv4 addresses always require OSPF to function inside a LAN.
This is wrong because private addresses can be used locally without any requirement for OSPF.
D
Distractor review
Public IPv4 addresses cannot exist on Internet-facing devices.
This is wrong because Internet-facing devices commonly use public addresses specifically to be reachable across the Internet.
E
Distractor review
Private and public IPv4 addresses are both automatically translated by ARP.
This is wrong because ARP resolves IP-to-MAC on a local link and does not perform private/public address translation.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is assuming that private IPv4 addresses can be routed on the Internet just like public addresses. This mistake often arises because private addresses function perfectly within a LAN and can communicate without special routing protocols. However, private addresses are intentionally non-routable on the public Internet to avoid address conflicts and preserve global uniqueness. Candidates may also confuse the need for routing protocols like OSPF with address type, mistakenly believing private addresses require OSPF to function internally, which is incorrect. Recognizing that private addresses require NAT for Internet access is crucial to avoid this trap.
Technical deep dive
How to think about this question
IPv4 addressing is divided into two main categories: private and public addresses. Private IPv4 addresses are defined by RFC 1918 and are reserved for use within private networks such as corporate LANs or home networks. These addresses are not routable on the public Internet, meaning routers on the Internet will not forward packets with private source or destination addresses. Public IPv4 addresses, on the other hand, are globally unique and assigned by Internet registries to ensure that devices using these addresses can communicate across the Internet without address conflicts. The fundamental rule governing private and public IPv4 addresses is their routability and uniqueness. Private addresses are intended solely for internal communication and require Network Address Translation (NAT) to communicate with public networks. Public addresses must be unique worldwide and are directly routable on the Internet. Cisco devices and CCNA exam scenarios often emphasize this distinction because it affects routing, NAT configuration, and security policies. Understanding which addresses are routable and which are not is critical for designing and troubleshooting networks. A common exam trap is confusing private address usability inside a LAN with their ability to be routed on the Internet. Many learners assume private addresses can be used anywhere without restriction, but they must be translated to public addresses for Internet access. Cisco devices use NAT to translate private addresses to public ones, enabling communication beyond the local network. Recognizing this separation helps avoid misconfigurations and clarifies why public addresses are necessary for Internet-facing interfaces.
KKey Concepts to Remember
- Private IPv4 addresses are reserved for internal network use and are not routable on the public Internet to prevent address conflicts.
- Public IPv4 addresses are globally unique and designed to be routable across the Internet without requiring translation.
- Network Address Translation (NAT) is required to allow devices with private IPv4 addresses to communicate with public Internet hosts.
- Cisco routers do not forward packets with private source or destination addresses across public Internet links by default.
- Private IPv4 address ranges are defined by RFC 1918 and include 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16.
- Public IPv4 addresses are assigned by Internet registries to ensure uniqueness and prevent routing conflicts globally.
- Private IPv4 addresses can be used freely inside LANs without routing protocols like OSPF, as they do not require Internet routing.
- Understanding the difference between private and public IPv4 addresses is essential for configuring NAT and designing secure network architectures.
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.
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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?
Private IPv4 addresses are reserved for internal network use and are not routable on the public Internet to prevent address conflicts.
What is the correct answer to this question?
The correct answer is: Private IPv4 addresses are not directly Internet-routable. — Private IPv4 addresses are intended for internal use and are not directly routable on the public Internet. In plain language, they are designed for use inside organizations, homes, and other local environments without consuming globally unique public space. Public addresses, by contrast, are intended to be unique and routable across the Internet. This is one of the main reasons NAT became so common in IPv4 environments. CCNA questions often test this distinction because learners sometimes confuse “valid inside a LAN” with “routable everywhere.” Private addressing is extremely useful, but it does not eliminate the need for translation or public addressing when reaching the Internet. The two correct statements are the ones that preserve that basic separation between internal-use ranges and globally routable address space.
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.
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