350-501 Networking Practice Question
An SP engineer is configuring IS-IS on a router and specifies a NET address of 49.0001.1921.6800.1001.00. What does the '00' at the end represent?
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
✓
SEL (NSAP Selector)
The last two octets of an IS-IS NET address represent the SEL (NSAP Selector), which is always 00 for a router.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
AFI
Why it's wrong here
AFI is the first octet, 49 in this case.
- ✗
System ID
Why it's wrong here
System ID is 6 bytes, not the last octet.
- ✗
Area ID
Why it's wrong here
Area ID is the middle portion after AFI.
- ✓
SEL (NSAP Selector)
Why this is correct
SEL identifies the network service user; 00 is for the routing protocol.
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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.