New information regarding this issue.
After spending all night troubleshooting, diagnosing, and being paranoid about the utopia.net DNS suffix, I've come to a conclusion.
This is in fact coming from the Cisco device and not from any networked clients and affects systems across multiple platforms, Windows 10 and Ubuntu 16.04 tested.
While the gateway is restarting (which does take some time), the ethernet connection is dropped, and re-established before the gateway is completely ready. While connected in this state, the client machine will use 10.0.0.1 as the DNS server and when it fails to resolve hostname, it then automatically tries to resolve to hostname.utopia.net The client machine then picks up on the suffix "utopia.net" and sets that as the connection-specific DNS suffix. Once the gateway is ready, the connection is re-established and DCHP gives the client machine an IP address and DNS servers of 22.214.171.124 and 126.96.36.199, but RETAINS the DNS suffix of "utopia.net". It is not until a DHCP renew is issued (if at all) that the DNS suffix changes to "hsd1.state.comcast.net".
For client machines with this behavior, the issue will occur each and every time the gateway is restarted.
Almost any hostname.utopia.net will resolve to one of their IP addresses and I'm not sure what purpose this serves and/or if any information may be collected by requests send to those servers. Also, as someone else mentioned, this even affects clients which are using manual DNS settings such as Google Public DNS (188.8.131.52, 184.108.40.206). Tested on fresh installations, safe modes, linux machines, factory gateway resets, and happens every time.
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