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Answer is an "it depends".
Many Cisco switches have QoS disabled by default. When so disabled, they generally pass marked packets "as is". However, many, when QoS enabled, will set ToS/CoS to zero unless configured to do otherwise.
Regarding whether you need the same QoS setup on all devices, that's another "it depends". "Book" answer is you configure QoS, to meet your goals, end-to-end. Insuring your QoS goals are met, end-to-end, though, doesn't always require identical QoS configurations or sometimes even a QoS configuration.
