Question 268 of 1,819
Network Infrastructure and ConnectivityhardTroubleshootingObjective-mapped

Quick Answer

The correct configuration is to assign R1’s G0/0 the IP address 192.168.1.1/24 and add a static route to 203.0.113.1/32 via next-hop 192.168.1.2, then configure R1’s G0/1 with the IPv6 address 2001:db8:acad:2::/64 eui-64. This works because the static route provides a path to R2’s loopback on a different subnet, while the EUI-64 command on G0/1 automatically generates the interface identifier from the MAC address, placing R1 on the correct 2001:db8:acad:2::/64 subnet to reach R3 directly. On the CCNA 200-301 v2 exam, this tests your ability to troubleshoot reachability by recognizing that a missing static route breaks connectivity to a remote loopback, and that EUI-64 addressing requires matching the subnet prefix to the neighbor’s network. A common trap is forgetting that EUI-64 does not change the subnet—you must specify the correct prefix before the eui-64 keyword. Memory tip: “Static for remote, EUI-64 for local subnet match.”

CCNA Network Infrastructure and Connectivity Practice Question

This 200-301 practice question tests your understanding of network infrastructure and connectivity. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 192.168.1.1 255.255.255.0
 no shutdown
!
interface GigabitEthernet0/1
 no ip address
 ipv6 address 2001:db8:acad:1::/64 eui-64
 no shutdown
!
interface GigabitEthernet0/2
 ip address 10.0.0.1 255.255.255.252
 no shutdown
!

R1# show ip interface brief
Interface              IP-Address      OK? Method Status                Protocol
GigabitEthernet0/0     192.168.1.1     YES manual up                    up
GigabitEthernet0/1     unassigned      YES manual up                    up
GigabitEthernet0/2     10.0.0.1        YES manual up                    up

R1# show ipv6 interface brief
GigabitEthernet0/1     [up/up]
    FE80::/10
    2001:DB8:ACAD:1:20C:29FF:FE12:3456

R1# ping 203.0.113.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 203.0.113.1, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)

R1# ping 2001:db8:acad:2::1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:DB8:ACAD:2::1, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)

(Information: R2's loopback is 203.0.113.1/32 reachable via R2's G0/0 192.168.1.2/24. R3's G0/0 is 2001:db8:acad:2::1/64, R3's G0/0 link-local is FE80::2.)

You are connected to R1 via the console. R1 has two directly connected routers: R2 and R3. Currently, R1 cannot reach R2's loopback interface (203.0.113.1/32). Additionally, R3 is IPv6-only and must be reachable from R1 using a statically assigned global unicast address. Configure R1's interfaces and static routes so that: (1) R1 can ping R2's loopback, (2) R1 can ping R3's IPv6 address 2001:db8:acad:2::1/64, and (3) R1's IPv6 address on the link to R3 is derived using EUI-64.

Question 1hardTroubleshooting
Study the full IPv6 explanation →

Exhibit

R1# show running-config | section interface
interface GigabitEthernet0/0
 ip address 192.168.1.1 255.255.255.0
 no shutdown
!
interface GigabitEthernet0/1
 no ip address
 ipv6 address 2001:db8:acad:1::/64 eui-64
 no shutdown
!
interface GigabitEthernet0/2
 ip address 10.0.0.1 255.255.255.252
 no shutdown
!

R1# show ip interface brief
Interface              IP-Address      OK? Method Status                Protocol
GigabitEthernet0/0     192.168.1.1     YES manual up                    up
GigabitEthernet0/1     unassigned      YES manual up                    up
GigabitEthernet0/2     10.0.0.1        YES manual up                    up

R1# show ipv6 interface brief
GigabitEthernet0/1     [up/up]
    FE80::/10
    2001:DB8:ACAD:1:20C:29FF:FE12:3456

R1# ping 203.0.113.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 203.0.113.1, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)

R1# ping 2001:db8:acad:2::1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:DB8:ACAD:2::1, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)

(Information: R2's loopback is 203.0.113.1/32 reachable via R2's G0/0 192.168.1.2/24. R3's G0/0 is 2001:db8:acad:2::1/64, R3's G0/0 link-local is FE80::2.)

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

Configure R1's G0/0 with IP 192.168.1.1/24 and add a static route to 203.0.113.1/32 via 192.168.1.2. Configure R1's G0/1 with IPv6 address 2001:db8:acad:2::/64 eui-64.

The ping to R2's loopback fails because R1's G0/0 is configured with a /24 mask, but the network should be /24 (which is correct), but the loopback is on a different subnet (203.0.113.0/24 vs 192.168.1.0/24). Actually the issue is that R1 has no route to 203.0.113.1. The solution is to add a static route on R1 pointing to R2's G0/0 IP. For IPv6, R1's EUI-64 address is on the wrong subnet (2001:db8:acad:1::/64) but R3 is on 2001:db8:acad:2::/64. The fix is to change the IPv6 address on R1's G0/1 to 2001:db8:acad:2::/64 eui-64. Then add an IPv6 static route if needed (but R1 and R3 are directly connected, so after fixing the subnet, ping should work).

Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Configure R1's G0/0 with IP 192.168.1.1/24 and add a static route to 203.0.113.1/32 via 192.168.1.2. Configure R1's G0/1 with IPv6 address 2001:db8:acad:2::/64 eui-64.

    Why this is correct

    This option correctly addresses both issues. The static route to R2's loopback (203.0.113.1/32) via next-hop 192.168.1.2 enables reachability. For IPv6, configuring G0/1 with the correct subnet (2001:db8:acad:2::/64) and using EUI-64 ensures R1 can ping R3's IPv6 address on the same subnet.

    Related concept

    CIDR notation defines the prefix length.

  • Configure R1's G0/0 with IP 192.168.1.1/24 and add a static route to 203.0.113.0/24 via 192.168.1.2. Configure R1's G0/1 with IPv6 address 2001:db8:acad:1::/64 eui-64.

    Why it's wrong here

    This is incorrect because the static route to 203.0.113.0/24 is too broad; it would work but the question specifies the loopback is a /32. More critically, the IPv6 address is on subnet 2001:db8:acad:1::/64, which is not the same as R3's subnet (2001:db8:acad:2::/64), so R1 cannot ping R3 directly.

  • Configure R1's G0/0 with IP 192.168.1.1/24 and add a static route to 203.0.113.1/32 via 192.168.1.2. Configure R1's G0/1 with IPv6 address 2001:db8:acad:2::1/64.

    Why it's wrong here

    This is incorrect because the IPv6 address on G0/1 is manually configured as 2001:db8:acad:2::1/64, which does not use EUI-64 as required. EUI-64 derives the interface ID from the MAC address, so the address must be configured with the eui-64 keyword.

  • Configure R1's G0/0 with IP 192.168.1.1/24 and add a static route to 203.0.113.1/32 via 192.168.1.2. Configure R1's G0/1 with IPv6 address 2001:db8:acad:1::/64 eui-64.

    Why it's wrong here

    This is incorrect because the IPv6 address is on subnet 2001:db8:acad:1::/64, which does not match R3's subnet (2001:db8:acad:2::/64). Even though EUI-64 is used, the subnet mismatch prevents direct ping to R3.

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.

Configure R1's G0/0 with IP 192.168.1.1/24 and add a static route to 203.0.113.1/32 via 192.168.1.2. Configure R1's G0/1 with IPv6 address 2001:db8:acad:2::/64 eui-64.Correct answer

Why this is correct

This option correctly addresses both issues. The static route to R2's loopback (203.0.113.1/32) via next-hop 192.168.1.2 enables reachability. For IPv6, configuring G0/1 with the correct subnet (2001:db8:acad:2::/64) and using EUI-64 ensures R1 can ping R3's IPv6 address on the same subnet.

Configure R1's G0/0 with IP 192.168.1.1/24 and add a static route to 203.0.113.0/24 via 192.168.1.2. Configure R1's G0/1 with IPv6 address 2001:db8:acad:1::/64 eui-64.Wrong answer — click to see why

Why this is wrong here

The IPv6 subnet mismatch prevents direct connectivity; R1 and R3 must be on the same subnet for a ping to work without additional routing.

Why candidates choose this

Candidates might think any /64 subnet works or that the static route to the loopback should match the network prefix rather than the host address.

Configure R1's G0/0 with IP 192.168.1.1/24 and add a static route to 203.0.113.1/32 via 192.168.1.2. Configure R1's G0/1 with IPv6 address 2001:db8:acad:2::1/64.Wrong answer — click to see why

Why this is wrong here

The requirement explicitly states that the IPv6 address must be derived using EUI-64; a manually specified interface ID violates this.

Why candidates choose this

Candidates may think that any valid IPv6 address on the correct subnet satisfies the requirement, overlooking the EUI-64 specification.

Configure R1's G0/0 with IP 192.168.1.1/24 and add a static route to 203.0.113.1/32 via 192.168.1.2. Configure R1's G0/1 with IPv6 address 2001:db8:acad:1::/64 eui-64.Wrong answer — click to see why

Why this is wrong here

The IPv6 subnet must be the same as R3's for direct connectivity; using a different subnet requires additional routing, which is not configured.

Why candidates choose this

Candidates might confuse the subnet for R1's link to R3 with another subnet or think EUI-64 automatically ensures reachability regardless of subnet.

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: usable hosts are not the same as total addresses

Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.

Trap categories for this question

  • Keyword trap

    This is incorrect because the IPv6 address on G0/1 is manually configured as 2001:db8:acad:2::1/64, which does not use EUI-64 as required. EUI-64 derives the interface ID from the MAC address, so the address must be configured with the eui-64 keyword.

Detailed technical explanation

How to think about this question

Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.

KKey Concepts to Remember

  • CIDR notation defines the prefix length.
  • Block size helps identify subnet boundaries.
  • Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
  • The required host count determines the smallest suitable subnet.

TExam Day Tips

  • Write the block size before choosing the subnet.
  • Check whether the question asks for hosts, subnets or a specific address range.
  • Do not confuse /24, /25, /26 and /27 host counts.

Key takeaway

Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.

Real-world example

How this comes up in practice

A network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.

What to study next

Got this wrong? Here's your next step.

Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related 200-301 subnetting questions on CIDR, address ranges, and subnet selection.

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.

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FAQ

Questions learners often ask

What does this 200-301 question test?

Network Infrastructure and Connectivity — This question tests Network Infrastructure and Connectivity — CIDR notation defines the prefix length..

What is the correct answer to this question?

The correct answer is: Configure R1's G0/0 with IP 192.168.1.1/24 and add a static route to 203.0.113.1/32 via 192.168.1.2. Configure R1's G0/1 with IPv6 address 2001:db8:acad:2::/64 eui-64. — The ping to R2's loopback fails because R1's G0/0 is configured with a /24 mask, but the network should be /24 (which is correct), but the loopback is on a different subnet (203.0.113.0/24 vs 192.168.1.0/24). Actually the issue is that R1 has no route to 203.0.113.1. The solution is to add a static route on R1 pointing to R2's G0/0 IP. For IPv6, R1's EUI-64 address is on the wrong subnet (2001:db8:acad:1::/64) but R3 is on 2001:db8:acad:2::/64. The fix is to change the IPv6 address on R1's G0/1 to 2001:db8:acad:2::/64 eui-64. Then add an IPv6 static route if needed (but R1 and R3 are directly connected, so after fixing the subnet, ping should work).

What should I do if I get this 200-301 question wrong?

Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related 200-301 subnetting questions on CIDR, address ranges, and subnet selection.

What is the key concept behind this question?

CIDR notation defines the prefix length.

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Last reviewed: Jun 6, 2026

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