Hi Peter,

Thank you for these clear answers. I am only just beginning my CCENT study with no prior knowledge of the basics behind it all. So things will become clearer as I work my way through the chapters. I am looking forward to become part of this community since you made it clear that questions can be asked and support is there when you need it.

Best Regards,

Jurgen

Hi Peter,

This is really a wonderful explanation, I'm definitely a fan of your way of explaining stuffs.

Regards

Alain

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Jurgen, I just wanted to add to a few points to what Peter has noted.

First, IP uniqueness is per routing topology.  It's possible to "reuse" IPs, but there shouldn't be duplicates within the same topology.

The reason I mention this first point, you might have already seen the example of hosts using "private" IPs, such as 192.168.x.x, that are duplicated between different locations.  For example, if you examine many home (Internet) users, and check their IPs, they might have the same host IP address.  The trick, though, is this network address is translated (NAT'ed) to an Internet unique IP at the Internet boundary.  (This technique has been the principle reason why we haven't run out of IPv4 Internet addresses years ago.)

Second, routers usually do not have individual host IP addresses  Instead, they carry network addresses.  Additionally, especially on the Internet, routers often have aggregate addresses that covers ranges of networks.  Peter's mention of using the default route is the "largest" aggregate.

The trick to aggregate addresses is to assign consecutive networks so they can be aggregated.

For example, if router A has four networks attached to it, 192.168.0.0/24, 192.168.1.0/24, 192.168.2.0/24, 192.168.3.0/24, instead of telling router B about all four networks, router A might tell router B it has, 192.168.0.0/22.  Then router B only has to deal with looking at one entry rather than four when deciding whether a packet should be sent to router A.

Jurgen, the above is probably a bit more than you looking for in your original question, but as you learn more you'll fine there's even more to learn.