CCNA Network Infrastructure and Connectivity Practice Question
This 200-301 practice question tests your understanding of network infrastructure and connectivity. 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.
Exhibit
R1#show running-config | section interface
interface GigabitEthernet0/0
ip address 198.51.100.1 255.255.255.0
no shutdown
!
interface GigabitEthernet0/1
ip address 203.0.113.1 255.255.255.0
no shutdown
!
interface GigabitEthernet0/2
no ip address
shutdown
!
R1#show ip interface brief
Interface IP-Address OK? Method Status Protocol
GigabitEthernet0/0 198.51.100.1 YES manual up up
GigabitEthernet0/1 203.0.113.1 YES manual up up
GigabitEthernet0/2 unassigned YES manual administratively down down
R1#ping 198.51.100.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 198.51.100.2, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
R1#ping 203.0.113.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 203.0.113.2, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
R1#show ipv6 interface brief
GigabitEthernet0/0 [administratively down/down]
GigabitEthernet0/1 [administratively down/down]
Note: R2 is on subnet 198.51.100.0/30, MLS1 is on subnet 203.0.113.0/30. Both R2 and MLS1 have correct IPs and are reachable via their respective subnets.
You are connected to R1. The network has R1, R2, and a multilayer switch MLS1. Configure IPv4 and IPv6 addressing on R1's interfaces so that R1 can ping both R2 (198.51.100.2) and MLS1 (203.0.113.2) via IPv4. Additionally, configure IPv6 on G0/1 using EUI-64 with prefix 2001:db8:1::/64 and verify that R1 can ping the IPv6 address of MLS1 (2001:db8:1::2). The current configuration has incorrect subnet masks and missing IPv6 settings, causing reachability failures.
R1#show running-config | section interface
interface GigabitEthernet0/0
ip address 198.51.100.1 255.255.255.0
no shutdown
!
interface GigabitEthernet0/1
ip address 203.0.113.1 255.255.255.0
no shutdown
!
interface GigabitEthernet0/2
no ip address
shutdown
!
R1#show ip interface brief
Interface IP-Address OK? Method Status Protocol
GigabitEthernet0/0 198.51.100.1 YES manual up up
GigabitEthernet0/1 203.0.113.1 YES manual up up
GigabitEthernet0/2 unassigned YES manual administratively down down
R1#ping 198.51.100.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 198.51.100.2, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
R1#ping 203.0.113.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 203.0.113.2, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
R1#show ipv6 interface brief
GigabitEthernet0/0 [administratively down/down]
GigabitEthernet0/1 [administratively down/down]
Note: R2 is on subnet 198.51.100.0/30, MLS1 is on subnet 203.0.113.0/30. Both R2 and MLS1 have correct IPs and are reachable via their respective subnets.
A
Change the subnet mask on G0/0 to 255.255.255.252, change G0/1 to 255.255.255.252, then configure IPv6 on G0/1 with the EUI-64 address using the prefix 2001:db8:1::/64.
This is correct because the /24 masks were causing R1 to believe R2 and MLS1 were on different subnets, preventing ARP resolution. Changing to /30 masks puts the interfaces on the correct point-to-point subnets. Configuring IPv6 with EUI-64 on G0/1 generates the interface ID from the MAC address, allowing R1 to ping MLS1's IPv6 address.
B
Change the subnet mask on G0/0 to 255.255.255.0, change G0/1 to 255.255.255.0, then configure IPv6 on G0/1 with the EUI-64 address using the prefix 2001:db8:1::/64.
Why wrong: This is incorrect because the /24 masks are the original problem; they do not provide the correct subnet boundaries for the point-to-point links. The IPv6 configuration is correct, but the IPv4 masks remain wrong, so pings will still fail.
C
Change the subnet mask on G0/0 to 255.255.255.252, change G0/1 to 255.255.255.252, then configure IPv6 on G0/1 with the static address 2001:db8:1::1/64.
Why wrong: This is incorrect because the IPv6 address must be generated using EUI-64 as specified in the question. Using a static address may not match the expected address on MLS1, and the question explicitly requires EUI-64.
D
Change the subnet mask on G0/0 to 255.255.255.252, change G0/1 to 255.255.255.252, then configure IPv6 on G0/1 with the EUI-64 address using the prefix 2001:db8:1::/32.
Why wrong: This is incorrect because the prefix length for the IPv6 address should be /64, not /32. Using a /32 prefix would place the interface on a much larger subnet, potentially causing routing issues and not matching MLS1's address.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Change the subnet mask on G0/0 to 255.255.255.252, change G0/1 to 255.255.255.252, then configure IPv6 on G0/1 with the EUI-64 address using the prefix 2001:db8:1::/64.
The interfaces on R1 were configured with subnet masks that were not /30, which is required for these point-to-point links. With an incorrect mask, R1 does not consider the neighboring IPs (198.51.100.2 and 203.0.113.2) as directly connected, preventing ARP resolution and IPv4 reachability. Additionally, IPv6 was missing on G0/1. To fix, change the subnet mask on G0/0 to 255.255.255.252, change G0/1 to 255.255.255.252, then configure IPv6 on G0/1 with the EUI-64 address using the prefix 2001:db8:1::/64. After these changes, pings succeed.
Key principle: OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Change the subnet mask on G0/0 to 255.255.255.252, change G0/1 to 255.255.255.252, then configure IPv6 on G0/1 with the EUI-64 address using the prefix 2001:db8:1::/64.
Why this is correct
This is correct because the /24 masks were causing R1 to believe R2 and MLS1 were on different subnets, preventing ARP resolution. Changing to /30 masks puts the interfaces on the correct point-to-point subnets. Configuring IPv6 with EUI-64 on G0/1 generates the interface ID from the MAC address, allowing R1 to ping MLS1's IPv6 address.
Change the subnet mask on G0/0 to 255.255.255.0, change G0/1 to 255.255.255.0, then configure IPv6 on G0/1 with the EUI-64 address using the prefix 2001:db8:1::/64.
Why it's wrong here
This is incorrect because the /24 masks are the original problem; they do not provide the correct subnet boundaries for the point-to-point links. The IPv6 configuration is correct, but the IPv4 masks remain wrong, so pings will still fail.
✗
Change the subnet mask on G0/0 to 255.255.255.252, change G0/1 to 255.255.255.252, then configure IPv6 on G0/1 with the static address 2001:db8:1::1/64.
Why it's wrong here
This is incorrect because the IPv6 address must be generated using EUI-64 as specified in the question. Using a static address may not match the expected address on MLS1, and the question explicitly requires EUI-64.
✗
Change the subnet mask on G0/0 to 255.255.255.252, change G0/1 to 255.255.255.252, then configure IPv6 on G0/1 with the EUI-64 address using the prefix 2001:db8:1::/32.
Why it's wrong here
This is incorrect because the prefix length for the IPv6 address should be /64, not /32. Using a /32 prefix would place the interface on a much larger subnet, potentially causing routing issues and not matching MLS1's address.
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.
✓Change the subnet mask on G0/0 to 255.255.255.252, change G0/1 to 255.255.255.252, then configure IPv6 on G0/1 with the EUI-64 address using the prefix 2001:db8:1::/64.Correct answer▾
Why this is correct
This is correct because the /24 masks were causing R1 to believe R2 and MLS1 were on different subnets, preventing ARP resolution. Changing to /30 masks puts the interfaces on the correct point-to-point subnets. Configuring IPv6 with EUI-64 on G0/1 generates the interface ID from the MAC address, allowing R1 to ping MLS1's IPv6 address.
✗Change the subnet mask on G0/0 to 255.255.255.0, change G0/1 to 255.255.255.0, then configure IPv6 on G0/1 with the EUI-64 address using the prefix 2001:db8:1::/64.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that /24 masks are too large for point-to-point links and do not match the expected subnets for R2 and MLS1.
Why candidates choose this
Candidates might think that keeping the /24 mask is fine because they are focusing only on IPv6, or they may not realize that the /24 mask causes R1 to believe the remote addresses are on different subnets.
✗Change the subnet mask on G0/0 to 255.255.255.252, change G0/1 to 255.255.255.252, then configure IPv6 on G0/1 with the static address 2001:db8:1::1/64.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the IPv6 address should be configured with the EUI-64 keyword, not a static address.
Why candidates choose this
Candidates might think that any IPv6 address in the same subnet will work, or they may be more comfortable with static addressing and overlook the EUI-64 requirement.
✗Change the subnet mask on G0/0 to 255.255.255.252, change G0/1 to 255.255.255.252, then configure IPv6 on G0/1 with the EUI-64 address using the prefix 2001:db8:1::/32.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the prefix length must be /64 as specified in the question; a /32 prefix is incorrect for this scenario.
Why candidates choose this
Candidates might confuse the prefix length with the network prefix or think that a shorter prefix is acceptable, not realizing that EUI-64 requires a /64 prefix.
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: OSPF can fail even when IP connectivity looks correct
OSPF neighbour formation depends on matching areas, timers, network type, authentication and passive-interface behaviour. Do not choose an answer only because the devices can ping.
Detailed technical explanation
How to think about this question
OSPF questions usually test the details that control adjacency and route selection. Read the neighbour state, area, router ID and interface configuration before deciding what is wrong.
KKey Concepts to Remember
OSPF neighbours must agree on key parameters.
Router ID selection can affect neighbour relationships and LSDB output.
OSPF cost influences the preferred path.
A route can appear in OSPF information but not become the installed route.
TExam Day Tips
→Check area mismatch first when OSPF adjacency fails.
→Review passive interfaces when a network is advertised but no neighbour forms.
→Use show ip ospf neighbor and show ip route clues carefully.
Key takeaway
OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Real-world example
How this comes up in practice
A network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.
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 OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 200-301 OSPF questions on adjacency and route selection.
Network Infrastructure and Connectivity — This question tests Network Infrastructure and Connectivity — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: Change the subnet mask on G0/0 to 255.255.255.252, change G0/1 to 255.255.255.252, then configure IPv6 on G0/1 with the EUI-64 address using the prefix 2001:db8:1::/64. — The interfaces on R1 were configured with subnet masks that were not /30, which is required for these point-to-point links. With an incorrect mask, R1 does not consider the neighboring IPs (198.51.100.2 and 203.0.113.2) as directly connected, preventing ARP resolution and IPv4 reachability. Additionally, IPv6 was missing on G0/1. To fix, change the subnet mask on G0/0 to 255.255.255.252, change G0/1 to 255.255.255.252, then configure IPv6 on G0/1 with the EUI-64 address using the prefix 2001:db8:1::/64. After these changes, pings succeed.
What should I do if I get this 200-301 question wrong?
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 200-301 OSPF questions on adjacency and route selection.
What is the key concept behind this question?
OSPF neighbours must agree on key parameters.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.