Question 1mediumdrag order
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Quick Answer
The correct order is PADI, PADO, PADR, PADS, followed by PPP LCP and authentication negotiation. This sequence is fundamental because PPPoE session establishment splits into two distinct phases: the Discovery stage, where the client locates and negotiates a session with an access concentrator, and the PPP stage, where the actual link control and security are set up. The client initiates by broadcasting a PADI (PPPoE Active Discovery Initiation), the server replies with a PADO (Offer), the client selects a server and sends a PADR (Request), and the server finalizes the session with a PADS (Session-confirmation) containing a unique session ID. Only after this four-way handshake does the PPP link begin, starting with LCP negotiation for link parameters and then authentication (PAP or CHAP). On the ENCOR 350-401 exam, this drag-and-drop task tests your ability to distinguish the discovery handshake from the subsequent PPP layer; a common trap is placing LCP before PADS. Remember the mnemonic “I Offer, Request, Session” to keep the discovery order straight, and note that PPP always comes after the session ID is assigned.
CCNP WAN Technologies Practice Question
This 350-401 practice question tests your understanding of wan technologies. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Drag and drop the steps of PPPoE session establishment into the correct order, from first to last.
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"first"Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
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
✓
Client sends PADI broadcast
PPPoE session establishment begins with the Discovery stage: the client sends a PADI to find a server, the server responds with a PADO, the client selects a server and sends a PADR, the server assigns a session ID via PADS. Finally, the PPP link is negotiated using LCP and authentication.
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.
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.
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 350-401 subnetting questions on CIDR, address ranges, and subnet selection.
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FAQ
Questions learners often ask
What does this 350-401 question test?
WAN Technologies — This question tests WAN Technologies — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Client sends PADI broadcast — PPPoE session establishment begins with the Discovery stage: the client sends a PADI to find a server, the server responds with a PADO, the client selects a server and sends a PADR, the server assigns a session ID via PADS. Finally, the PPP link is negotiated using LCP and authentication.
What should I do if I get this 350-401 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 350-401 subnetting questions on CIDR, address ranges, and subnet selection.
Are there clue words in this question I should notice?
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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Last reviewed: Jun 18, 2026
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