Final answer:
To find the IPv6 source address of the 20th packet's DNS AAAA request, you need to view the packet details in a Wireshark trace and look at the IPv6 section of the packet header.
Step-by-step explanation:
The question pertains to identifying the IPv6 address of a computer that has made a DNS AAAA request. In a packet trace captured by a tool like Wireshark, each packet is listed along with its details, such as source and destination addresses, protocols used, etc. To find the IPv6 source address of the 20th packet, one would need to open the packet trace in Wireshark, navigate to the 20th packet, and look at the packet details. Specifically, the source IPv6 address would be displayed in the IPv6 section of the packet header information. This address appears as a sequence of eight groups of four hexadecimal digits, separated by colons, for example, 2001:0db8:85a3:0000:0000:8a2e:0370:7334.