Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
A network administrator is configuring Quality of Service (QoS) on a router to prioritize voice traffic. Which of the following fields should be used to mark packets for classification and prioritization?
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
Distractor review
Source IP address
Source IP address can be used to classify traffic but does not mark the packet; marking is done by setting a specific field so downstream devices can prioritize based on the mark, not the original source.
B
Best answer
DSCP
DSCP is a 6-bit field in the IP header used for packet classification and prioritization in QoS. It allows consistent priority handling across the network.
C
Distractor review
Source port number
Port numbers are transport layer identifiers; they can be used for classification but not for marking per se; DSCP is the standard marking method.
D
Distractor review
MAC address
MAC addresses are used at Layer 2 for local delivery and are not suitable for marking packets for end-to-end QoS.
Common exam trap
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Technical deep dive
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
- Standard ACLs match source addresses.
- Extended ACLs can match source, destination, protocol and ports.
- The first matching ACL entry is used.
- There is usually an implicit deny at the end.
TExam Day Tips
- Check inbound versus outbound direction.
- Read the ACL from top to bottom.
- Look for a broader permit or deny above the intended line.
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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 network engineer needs to connect two switches located 400 meters apart. The cable run includes high electromagnetic interference from nearby machinery. The engineer decides to use fiber optic cabling. Which transceiver type and fiber combination should be used to ensure the link reaches 400 meters while remaining cost-effective?
Question 2
A network engineer is designing a new switched network and needs to ensure that broadcast traffic from one department does not reach another department's workstations. The engineer plans to use VLANs. Which of the following must be configured on the switches to isolate broadcast domains as intended?
Question 3
A security engineer is configuring a site-to-site VPN between two branch offices. The requirement is to encrypt all traffic between the two networks using IPsec. Which IPsec mode should be used to encrypt the entire IP packet including the original header?
Question 4
A network administrator is connecting two switches to increase bandwidth and provide redundancy. Which technology should be used to combine multiple physical links into a single logical link?
Question 5
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Question 6
A network administrator is troubleshooting a connectivity issue and suspects the problem is related to the physical cabling. At which layer of the OSI model should the administrator begin their investigation?
FAQ
Questions learners often ask
What does this N10-009 question test?
Standard ACLs match source addresses.
What is the correct answer to this question?
The correct answer is: DSCP — QoS marking uses the Differentiated Services Code Point (DSCP) field in the IP header (Layer 3). DSCP allows traffic to be classified and prioritized across the network. Source IP addresses and port numbers can be used for classification via ACLs, but marking ensures that priority is maintained even if the packet traverses multiple routers. MAC addresses are Layer 2 and not typically used for QoS marking in routed networks.
What should I do if I get this N10-009 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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