350-501 Networking Practice Question
In IS-IS, what is the purpose of the NET (Network Entity Title) address field SEL (Selector) byte?
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
✓
Indicates that this is a router (always 0x00)
The SEL byte is always 0x00 for routers, indicating that the address refers to the router itself rather than a specific service.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Identifies the application layer protocol
Why it's wrong here
SEL is for NSAP; for routers it is 0x00.
- ✓
Indicates that this is a router (always 0x00)
Why this is correct
SEL=0x00 indicates the network entity.
- ✗
Identifies the area
Why it's wrong here
Area is identified by the Area portion.
- ✗
Identifies the system ID
Why it's wrong here
System ID is separate.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-501 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 350-501 exam.