&gt; &quot;It turns out their system had my modem MAC address entered incorrectly, there was an off-by-one typo that was hard to see so they were counting data from some modem who knows where,&quot;<p>how unlikely is this, really?<p>a MAC address is 48 bits or 6 hex digits. what are the odds that mistyping one of those digits resolves to a MAC address of another Comcast customer?<p>are they assigned randomly?<p>why are people at Comcast <i>typing</i> in MAC addresses in situations as serious as billing and metering, in the first place?