350-501 Networking Practice Question
In an IS-IS network, a router has a NET 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 byte '00' is the SEL (NSAP Selector), which is always '00' for IS-IS routing.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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System ID
Why it's wrong here
System ID is 1921.6800.1001.
- ✓
SEL (NSAP Selector)
Why this is correct
SEL is always 00 for IS-IS.
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AFI
Why it's wrong here
AFI is 49.
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Area ID
Why it's wrong here
Area ID is 0001 in this NET.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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