What does 'CPE' stand for, and what is it?

Question

In reading up on NextDNS, I came across the add-cpe-id option to dnsmasq:

--add-cpe-id=
Add an arbitrary identifying string to DNS queries which are forwarded upstream.

NextDNS uses this for your 'endpoint ID', basically an account/profile identifier.

But what does CPE stand for, and how/where is this arbitrary string added to the query?

There seem to be vanishingly few results for 'CPE ID DNS' or '~ DHCP' that seem relevant, and none of those I've found spells it out or explains what it is (just e.g. how to configure on Cisco equipment, or similar). The dnsmasq man page quoted above is by far the clearest I've found - but how does an arbitrary string come to be called 'CPE'? There's a question on this site from someone with '5 models of CPE', and it's a 'thing' that has a MAC address - is that the same CPE? If so what is it?

Answer 1

CPE usually stands for customer premises equipment - a router or modem that is supplied by a provider. The opposite is central office equipment COE.

A CPE ID is used to uniquely identify a customer-side device to the central (ISP) infrastructure, most often used for AAA. It may be used in the context of DNS, DHCP or RADIUS, but what exactly it is used for and how it works depends on the network design.