4A0-104 practice question 5 of 35
On a dot1Q encapsulated port, frames with a VLAN tag of 0 and untagged frames are forwarded to the null SAP
Full set: 288 questionsCorrect Answer:
A. TRUE
Explanation
On a dot1q-encapsulated access port, any frame that arrives with VLAN tag 0 (priority-tagged) or arrives untagged is associated with the predefined null SAP. The null SAP discards the traffic unless it is explicitly bound to a service.
Why Incorrect
B. (False) Frames with VLAN 0/untagged are not matched to regular SAPs; they map to the null SAP as documented.
References
1. Nokia 7750 SR OS Service Configuration Guide, 23.10.R1, “SAP Encapsulation – dot1q”, p. 421, para 3.
2. IEEE 802.1Q-2018, sec. 12.13.2 – definition of priority-tagged (VLAN 0) frames and provider handling.
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