CCNA Network Infrastructure and Connectivity Practice Question
Which two statements accurately compare IPv4 private addresses and public addresses?
⚠ Common exam trap
Be careful not to confuse the routability of private addresses with their validity within a LAN. Private addresses need NAT for Internet access.
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
✓
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.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Private IPv4 addresses are not directly Internet-routable.
Why this is correct
Correct because RFC 1918 defines private ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) that are not globally routable; Internet routers are configured to discard packets with these source or destination addresses. This is enforced by ISPs and core routers to prevent conflicts and routing loops, since these addresses are reused by countless internal networks. To access the Internet, private addresses must be translated to a public address using NAT.
- ✓
Public IPv4 addresses are intended to be globally unique and routable.
Why this is correct
Correct because public IPv4 addresses are assigned by IANA/RIRs to ensure no two devices on the public Internet share the same address, guaranteeing global uniqueness. Routers on the Internet maintain routes to these addresses, allowing packets to be forwarded across autonomous systems to reach the destination. This global uniqueness and routeability are fundamental to the operation of the Internet.
- ✗
Private IPv4 addresses always require OSPF to function inside a LAN.
Why it's wrong here
This is wrong because private IPv4 addresses can be used with any routing protocol, including static routes, RIP, EIGRP, or even no routing protocol on a single-switch LAN. OSPF is a link-state routing protocol designed for larger enterprise networks, not a mandatory requirement for private addressing. Inside a simple LAN, hosts with private addresses communicate via ARP and Layer 2 switching without any dynamic routing protocol.
When this WOULD be correct
If the question were to ask about the requirements for routing protocols in a specific network setup that exclusively uses OSPF for all internal communications, then this statement could be correct. For example, a scenario where a network design mandates OSPF for all routing, including private addresses, would validate this option.
- ✗
Public IPv4 addresses cannot exist on Internet-facing devices.
Why it's wrong here
This is incorrect because Internet-facing devices such as web servers, routers, and firewalls are typically assigned public IPv4 addresses precisely to be reachable from anywhere on the Internet. The entire purpose of public addressing is to enable global communication; without a public address, a device cannot initiate or receive direct inbound traffic from external networks. Therefore, public IPv4 addresses absolutely do and must exist on Internet-facing devices.
When this WOULD be correct
If the exam question stated that 'Public IPv4 addresses are only used in private networks' or 'Public IPv4 addresses are never assigned to devices that connect directly to the Internet,' then option D would be correct. Such a scenario would misrepresent the nature of public IP addresses.
- ✗
Private and public IPv4 addresses are both automatically translated by ARP.
Why it's wrong here
This is wrong because ARP (Address Resolution Protocol) operates within a single local network segment to map an IPv4 address to a corresponding MAC address; it does not perform network address translation (NAT) between private and public addressing. Private-to-public translation is performed by NAT/PAT on routers or firewalls, not by ARP. ARP has no concept of public or private address categories and simply resolves IP-to-hardware addresses for any IPv4 address on the local link.
When this WOULD be correct
In a question that asks about the functions of ARP in a network where both private and public addressing schemes are in use, one might state that ARP is involved in the translation process, making this option correct in that context.
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.
✓Private IPv4 addresses are not directly Internet-routable.Correct answer▾
Why this is correct
Correct because RFC 1918 defines private ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) that are not globally routable; Internet routers are configured to discard packets with these source or destination addresses. This is enforced by ISPs and core routers to prevent conflicts and routing loops, since these addresses are reused by countless internal networks. To access the Internet, private addresses must be translated to a public address using NAT.
✗Private IPv4 addresses always require OSPF to function inside a LAN.Wrong answer — click to see why▾
Why this is wrong here
Private IPv4 addresses do not require OSPF or any specific routing protocol to function inside a LAN; they can operate with static routes or any dynamic routing protocol. OSPF is just one option and is not mandatory.
★ When this WOULD be the correct answer
If the question were to ask about the requirements for routing protocols in a specific network setup that exclusively uses OSPF for all internal communications, then this statement could be correct. For example, a scenario where a network design mandates OSPF for all routing, including private addresses, would validate this option.
Why candidates choose this
Students might associate private addresses with internal networks and mistakenly think OSPF is commonly used there, but OSPF is not a requirement for private address operation.
✗Public IPv4 addresses cannot exist on Internet-facing devices.Wrong answer — click to see why▾
Why this is wrong here
Public IPv4 addresses are specifically used on Internet-facing devices to enable global reachability. Without public addresses, devices would not be directly accessible from the Internet.
★ When this WOULD be the correct answer
If the exam question stated that 'Public IPv4 addresses are only used in private networks' or 'Public IPv4 addresses are never assigned to devices that connect directly to the Internet,' then option D would be correct. Such a scenario would misrepresent the nature of public IP addresses.
Why candidates choose this
A student might confuse public addresses with private ones, thinking public addresses are only for internal use, but the opposite is true.
✗Private and public IPv4 addresses are both automatically translated by ARP.Wrong answer — click to see why▾
Why this is wrong here
ARP (Address Resolution Protocol) resolves IP addresses to MAC addresses on a local network segment and does not perform any translation between private and public addresses. NAT (Network Address Translation) handles that translation.
★ When this WOULD be the correct answer
In a question that asks about the functions of ARP in a network where both private and public addressing schemes are in use, one might state that ARP is involved in the translation process, making this option correct in that context.
Why candidates choose this
The acronym 'ARP' might be confused with 'NAT' or 'PAT' by students who are not clear on the functions of each protocol.
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?”
Visual reference
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
Go deeper
Related to this question
Learn chapter
IPv4 Addressing and Address Classes
Key term
Internet Protocol
Internet Protocol (IP) is the set of rules that governs how data is addressed, routed, and sent from one device to another across networks, including the internet.
Key term
LAN
Local Area Network — a network confined to a single physical location such as an office, building, or campus.
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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.