Final answer:
The default CoS value for Voice Data packets is typically 5, indicating a high priority to ensure quality in VoIP communication.
Step-by-step explanation:
The default CoS value for Voice Data packets is typically 5. CoS, which stands for Class of Service, is a field in an Ethernet frame header that prioritizes different types of data. Voice traffic is often given a high priority because it is sensitive to delays and packet loss which can significantly degrade the quality of a voice call. For instance, in a VoIP (Voice over IP) setup, where voice data is transmitted over a data network, it is important to ensure that voice packets receive priority over less time-sensitive data, such as email.