Question 1,653 of 2,152
Device ManagementmediumMultiple ChoiceObjective-mapped

EIGRP Network Statement Behavior

This 300-410 practice question tests your understanding of device management. 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.

Given the following partial configuration on router R1:

router eigrp 100
 network 10.0.0.0 0.255.255.255
 network 192.168.1.0 0.0.0.255

!

interface GigabitEthernet0/0
 ip address 10.1.1.1 255.255.255.0

!

interface GigabitEthernet0/1
 ip address 192.168.1.1 255.255.255.0

!

interface GigabitEthernet0/2
 ip address 172.16.1.1 255.255.255.0

What is the effect of this configuration?

Quick Answer

The answer is that EIGRP will only advertise the 10.1.1.0/24 and 192.168.1.0/24 networks, while the 172.16.1.0/24 network will be ignored for both advertisement and adjacency formation. This occurs because the EIGRP network statement behavior uses a wildcard mask to match interfaces, not the network prefix itself; the interface’s primary IP address must fall within the range defined by the network statement and its wildcard mask. In this configuration, the network 10.0.0.0 0.255.255.255 matches the 10.1.1.1 interface, and network 192.168.1.0 0.0.0.255 matches the 192.168.1.1 interface, but no statement covers the 172.16.1.1 interface. On the Cisco CCNP ENARSI 300-410 exam, this tests your understanding that EIGRP network statements are interface-selection tools, not route filters—a common trap is assuming a classful network 172.16.0.0 is automatically included. Remember the memory tip: “EIGRP networks match interfaces, not routes—if the IP doesn’t land in the wildcard range, it’s a stranger.”

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

EIGRP will only advertise the 10.1.1.0/24 and 192.168.1.0/24 networks; the 172.16.1.0/24 network will not be advertised and no EIGRP adjacency will be formed on that interface.

Option B is correct because EIGRP uses the network command with a wildcard mask to determine which interfaces to enable EIGRP on. The network 10.0.0.0 0.255.255.255 matches interfaces with an IP address in the 10.x.x.x range, enabling EIGRP on GigabitEthernet0/0 (10.1.1.1). The network 192.168.1.0 0.0.0.255 matches the 192.168.1.0/24 subnet, enabling EIGRP on GigabitEthernet0/1 (192.168.1.1). The 172.16.1.0/24 network is not matched by any network statement, so EIGRP is not enabled on GigabitEthernet0/2, and no adjacency is formed there.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

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

  • EIGRP will form adjacencies and advertise all three interfaces because the network statements use classful boundaries.

    Why it's wrong here

    The network 172.16.1.0 is not covered by any network statement; 10.0.0.0 covers 10.1.1.0/24, and 192.168.1.0 covers 192.168.1.0/24, but 172.16.1.0/24 is not included.

  • EIGRP will only advertise the 10.1.1.0/24 and 192.168.1.0/24 networks; the 172.16.1.0/24 network will not be advertised and no EIGRP adjacency will be formed on that interface.

    Why this is correct

    Only interfaces matching the network statements are enabled for EIGRP. 172.16.1.0/24 does not match 10.0.0.0 or 192.168.1.0, so it is excluded.

    Related concept

    Read the scenario before looking for a memorised answer.

  • EIGRP will advertise all three networks because the network 10.0.0.0 command includes all interfaces with an IP starting with 1, 172, or 192.

    Why it's wrong here

    The network 10.0.0.0 command only matches interfaces whose IP address falls within the 10.0.0.0/8 range, not 172.16.x.x or 192.168.x.x.

  • EIGRP will not form any adjacencies because the network statements must use exact subnet masks instead of wildcard masks.

    Why it's wrong here

    EIGRP network statements can use wildcard masks; the configuration is valid. The issue is the missing network statement for 172.16.1.0/24.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Cisco often tests the misconception that a network statement with a wildcard mask will automatically include all interfaces with similar first octets, but in reality, the wildcard mask must explicitly match the exact subnet range for an interface to be enabled.

Trap categories for this question

  • Command / output trap

    The network 10.0.0.0 command only matches interfaces whose IP address falls within the 10.0.0.0/8 range, not 172.16.x.x or 192.168.x.x.

Detailed technical explanation

How to think about this question

Under the hood, EIGRP uses the network command to enable the protocol on interfaces whose IP address falls within the specified range, using a wildcard mask for bitwise matching. If no wildcard mask is provided, EIGRP defaults to the classful boundary (e.g., network 10.0.0.0 enables EIGRP on all interfaces with a 10.x.x.x address). In this configuration, the explicit wildcard masks restrict matching to the 10.0.0.0/8 and 192.168.1.0/24 ranges, leaving the 172.16.1.0/24 interface passive to EIGRP. A real-world scenario is when an administrator wants to enable EIGRP only on specific subnets within a major network, using wildcard masks to avoid advertising all interfaces.

KKey Concepts to Remember

  • Read the scenario before looking for a memorised answer.
  • Find the constraint that changes the correct option.
  • Eliminate answers that are true in general but not in this case.

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.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

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.

Visual reference

192.168.1.0 /24 256 addresses (254 usable) 192.168.1.0 /25 Subnet A 128 addr (126 usable) 192.168.1.128 /25 Subnet B 128 addr (126 usable) Borrowing 1 bit from host portion creates 2 subnets (/25)

Quick reference

Routing Protocol Comparison

ProtocolMetricMax HopsAlgorithmType
RIP v2Hop count15Bellman-FordDistance vector
OSPFCost (bandwidth)UnlimitedDijkstra (SPF)Link state
EIGRPComposite metricUnlimitedDUALHybrid
IS-ISCostUnlimitedDijkstraLink state
BGPPolicy / attributesUnlimitedPath vectorPath vector

RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.

What to study next

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FAQ

Questions learners often ask

What does this 300-410 question test?

Device Management — This question tests Device Management — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: EIGRP will only advertise the 10.1.1.0/24 and 192.168.1.0/24 networks; the 172.16.1.0/24 network will not be advertised and no EIGRP adjacency will be formed on that interface. — Option B is correct because EIGRP uses the network command with a wildcard mask to determine which interfaces to enable EIGRP on. The network 10.0.0.0 0.255.255.255 matches interfaces with an IP address in the 10.x.x.x range, enabling EIGRP on GigabitEthernet0/0 (10.1.1.1). The network 192.168.1.0 0.0.0.255 matches the 192.168.1.0/24 subnet, enabling EIGRP on GigabitEthernet0/1 (192.168.1.1). The 172.16.1.0/24 network is not matched by any network statement, so EIGRP is not enabled on GigabitEthernet0/2, and no adjacency is formed there.

What should I do if I get this 300-410 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Last reviewed: Jul 4, 2026

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