The correct answer is that QPPB uses BGP communities to mark QoS on traffic received from a customer, and it can be applied on the inbound direction only. This is because QoS Policy Propagation via BGP leverages BGP community attributes to classify incoming traffic into IP precedence or QoS groups before any routing decision is made, allowing the router to apply differentiated treatment based on the customer’s BGP path attributes. On the Cisco SPCOR 350-501 exam, this concept tests your understanding of how service providers can propagate QoS policies across an autonomous system without complex per-interface configurations. A common trap is assuming QPPB works on outbound traffic, but the classification is strictly inbound—once the packet is routed, the QoS marking is already set. Remember the mnemonic: “BGP in, QoS out” is wrong; think “BGP in, QoS in” to keep the direction straight.
350-501 Services Practice Question
This 350-501 practice question tests your understanding of services. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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.
Which TWO statements about QoS policy propagation via BGP (QPPB) are correct?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
QPPB can be applied on inbound direction only.
Option A is correct because QPPB can be applied on inbound direction only. QPPB uses BGP policy to classify traffic based on IP precedence or QoS group, and the classification is performed on incoming traffic before any routing decision. The outbound direction is not supported for QPPB classification.
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.
✓
QPPB can be applied on inbound direction only.
Why this is correct
It applies to traffic coming from customers.
Related concept
Read the scenario before looking for a memorised answer.
✗
QPPB is an IETF standard.
Why it's wrong here
QPPB is Cisco proprietary.
✓
It uses BGP communities to mark QoS on traffic received from customer.
It dynamically adjusts BGP attributes based on QoS policy.
Why it's wrong here
It is the opposite: BGP attributes influence QoS marking.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that QPPB is an IETF standard or that it can be applied bidirectionally, when in fact it is a Cisco proprietary feature limited to inbound direction only.
Detailed technical explanation
How to think about this question
QPPB leverages BGP communities to map incoming traffic to a specific QoS policy. For example, a service provider can set a BGP community on routes received from a customer, and then use a route-map to classify traffic matching that community into a particular QoS group or IP precedence. This allows per-customer or per-prefix QoS without complex ACLs, and is often used in MPLS VPN environments to differentiate traffic from different customers.
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 practitioner preparing for the 350-501 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Services — This question tests Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: QPPB can be applied on inbound direction only. — Option A is correct because QPPB can be applied on inbound direction only. QPPB uses BGP policy to classify traffic based on IP precedence or QoS group, and the classification is performed on incoming traffic before any routing decision. The outbound direction is not supported for QPPB classification.
What should I do if I get this 350-501 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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Question Discussion
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