I am still struggling to understand to what extent CIDR really renders IP address classes obsolete. Here's what I understood so far:

1. It's ridiculously inefficient (and impossible, too) to assign every organization that needs to address more than 255 hosts a class B address, which could technically address 65535 hosts.
2. However, if such an organization needed to address, say, approximately 700 hosts, one could just assign three (preferably contiguous) class C network addresses to that organization. E.g.:

```
192.42.42
192.42.43
192.42.44

```
3. Problem: For that *one* organization, routers would have to store *three* entries in their forwarding tables, which won't scale.
4. CIDR solves this problem by introducing route summarization/aggregation, enabling the ISP that assigned the three class C networks to the organization to advertise only *one* prefix to the rest of the world. E.g.,

```
192.42.42.0/21

```

So far, so good. However, I just can't grasp why every resource I touch claims that classful addressing is "a thing of the past". After all, the ISP *is* in charge of, say, class C network addresses, and *does* assign these to its customers. CIDR just fixes the problem of multiple entries in the forwarding tables, right? Thus, IP address classes are still around, are they not?

Exam's coming up, so help is much appreciated. :P