What CoS value does a Cisco IP phone assign to traffic received from a host on its access port by default?

What CoS value does a Cisco IP phone assign to traffic received from a host on its access port by default?

• A. 0
• B. 7
• C. 3
• D. 5

Answer: (A)

Traffic from a host on the phone’s access port is treated as data, not voice. The phone’s built–in switch forwards data frames with the default, best‑effort CoS value, which is 0. The phone does itself mark its own voice traffic with a higher CoS (5) when sending toward the network, and often maps voice to a dedicated VLAN with DSCP EF, but that marking applies to voice traffic generated by the phone, not to the data coming from the host. So, by default, host traffic on the access port uses CoS 0.

Traffic from a host on the phone’s access port is treated as data, not voice. The phone’s built–in switch forwards data frames with the default, best‑effort CoS value, which is 0. The phone does itself mark its own voice traffic with a higher CoS (5) when sending toward the network, and often maps voice to a dedicated VLAN with DSCP EF, but that marking applies to voice traffic generated by the phone, not to the data coming from the host. So, by default, host traffic on the access port uses CoS 0.