  We continue to see increasingly widespread deployment of IoT devices, with
apparent intent to embed them in our built environment likely to accelerate if
smart city and related programmes succeed. In this paper we are concerned with
the ways in which current generation IoT devices are being designed in terms of
their ill-considered dependencies on network connectivity and services. Our
hope is to provide evidence that such dependencies need to be better thought
through in design, and better documented in implementation so that those
responsible for deploying these devices can be properly informed as to the
impact of device deployment (at scale) on infrastructure resilience. We believe
this will be particularly relevant as we feel that commodity IoT devices are
likely to be commonly used to retrofit `smart' capabilities to existing
buildings, particularly domestic buildings.
  To the existing body of work on network-level behaviour of IoT devices, we
add \one~a protocol-level breakdown and analysis of periodicity, \two~an
exploration of the service and infrastructure dependencies that will implicitly
be taken in `smart' environments when IoT devices are deployed, and
\three~examination of the robustness of device operation when connectivity is
disrupted. We find that many devices make use of services distributed across
the planet and thus appear dependent on the global network infrastructure even
when carrying out purely local actions. Some devices cease to operate properly
without network connectivity (even where their behaviour appears, on the face
of it, to require only local information, e.g.,~the Hive thermostat). Further,
they exhibit quite different network behaviours, typically involving
significantly more traffic and possibly use of otherwise unobserved protocols,
when connectivity is recovered after some disruption.
