Question 1mediummulti select
Full question →mediummulti selectObjective-mapped
Which two statements accurately describe subnet masks in IPv4?
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
It identifies the network-versus-host split in an IPv4 address.
This is correct because that is the primary function of the subnet mask.
B
Best answer
It helps a host determine whether a destination is local or remote.
This is correct because the subnet mask defines local network scope.
C
Distractor review
It resolves hostnames into IP addresses.
This is wrong because DNS performs hostname resolution.
D
Distractor review
It encrypts packets before they leave the host.
This is wrong because subnet masks do not provide encryption.
E
Distractor review
It replaces the need for a default gateway.
This is wrong because hosts still need a gateway for off-subnet traffic.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is mistaking the subnet mask for a function that performs hostname resolution or encryption. Some candidates incorrectly believe the subnet mask helps translate domain names to IP addresses or encrypts data before transmission. These are incorrect because DNS servers handle hostname resolution, and encryption is managed by security protocols, not subnet masks. This confusion can lead to selecting wrong answers that attribute unrelated network functions to subnet masks. Understanding the subnet mask’s true role in defining network boundaries and routing decisions is crucial to avoid this pitfall.
Technical deep dive
How to think about this question
A subnet mask in IPv4 networking is a 32-bit binary pattern that divides an IP address into network and host portions. It works by masking the IP address bits to identify which part refers to the network and which part refers to the host device within that network. This division is fundamental for routing and addressing because it defines the scope of a local subnet and enables devices to communicate efficiently within and outside their networks. When a host sends a packet, it uses the subnet mask to determine if the destination IP address is within the same subnet or a remote network. If the destination falls within the subnet mask's network range, the host sends the packet directly using ARP to resolve the MAC address. If the destination is outside the subnet, the host forwards the packet to the configured default gateway for routing. This decision-making process is critical in Cisco devices and the CCNA exam context because it impacts traffic flow and network segmentation. A common exam trap is confusing the subnet mask’s role with other network functions like DNS resolution or encryption. Subnet masks do not translate hostnames to IP addresses nor encrypt data; these functions belong to DNS and security protocols, respectively. Understanding this distinction helps avoid selecting incorrect answers that attribute unrelated functions to subnet masks. Practically, subnet masks enable efficient IP address management and proper routing decisions, which are essential for network design and troubleshooting in Cisco environments.
KKey Concepts to Remember
- A subnet mask determines which bits of an IPv4 address represent the network and which bits represent the host portion.
- Hosts use the subnet mask to decide if a destination IP address is local or remote, affecting packet forwarding behavior.
- If the destination is local, the host uses ARP to resolve the MAC address and send packets directly within the subnet.
- If the destination is remote, the host forwards packets to the default gateway for routing outside the local subnet.
- Subnet masks do not perform hostname resolution; DNS servers handle translating hostnames to IP addresses.
- Subnet masks do not provide encryption or security functions; encryption is handled by protocols like IPsec or SSL.
- Proper subnet mask configuration is essential for network segmentation, efficient IP address utilization, and routing accuracy.
- Misunderstanding subnet mask functions can lead to incorrect assumptions about network behavior and routing decisions.
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.
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.
CCNA subnetting practice questions
Practise IPv4 subnetting, CIDR, masks, host ranges and subnet selection.
CCNA OSPF practice questions
Practise OSPF neighbours, router IDs, metrics, areas and routing-table interpretation.
CCNA VLAN practice questions
Practise VLANs, access ports, trunks, allowed VLANs and switching scenarios.
CCNA STP practice questions
Practise spanning tree, root bridge election, port roles and STP troubleshooting.
CCNA EtherChannel practice questions
Practise LACP, PAgP, port-channel behaviour and bundle requirements.
CCNA ACL practice questions
Practise standard and extended ACLs, permit/deny logic and traffic filtering.
CCNA NAT practice questions
Practise static NAT, dynamic NAT, PAT and inside/outside address translation.
CCNA DHCP practice questions
Practise DHCP scopes, relay, leases and troubleshooting.
CCNA show ip route practice questions
Practise routing-table output, longest-prefix match, AD and route selection.
CCNA show interfaces trunk practice questions
Practise trunk verification and VLAN forwarding across switches.
CCNA wireless security practice questions
Practise WLAN security, authentication and wireless architecture concepts.
CCNA IPv6 practice questions
Practise IPv6 addressing, routes, neighbour discovery and common IPv6 exam traps.
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?
A subnet mask determines which bits of an IPv4 address represent the network and which bits represent the host portion.
What is the correct answer to this question?
The correct answer is: It identifies the network-versus-host split in an IPv4 address. — A subnet mask tells the host which part of the IPv4 address refers to the network and which part refers to the host. In plain language, it helps the device determine whether a destination is local or remote. That decision is essential because it affects whether the host uses ARP directly or forwards traffic to the default gateway. The wrong answers usually attribute unrelated behaviors to the subnet mask, such as encryption or hostname resolution. The two correct answers are the ones that preserve its role in defining local scope and address structure.
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.
Discussion
Loading comments…
Sign in to join the discussion.