Please comment on the examples below.
Example 1:
lan0 has number 192.168.0.1 and 192.168.0.2

Example 2:
lan0 has 192.168.0.1
lan1 has 192.168.0.2

Example 3: /etc/hosts file:
192.168.0.1 cheetah.bigcats.com cheetah giga
192.168.0.2 cheetah.bigcats.com cheetah hundred

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In my opinion all three cases are wrong or at least not the proper way. Where can I find info about what is not nice or what is really wrong?
-Rene

Hopefully this isn't homework - I checked and it seems like you answer questions with knowledge about UNIX so it would seem you are just asking a question.

So,

Example 1:
lan0 has number 192.168.0.1 and 192.168.0.2

One possible reason to have this - one address is used for ftp, one is used for mail (different names in dns). Otherwise, it seems to be a waste of an IP.

Example 2:
lan0 has 192.168.0.1
lan1 has 192.168.0.2
Same reasoning as Example one just that it has two interfaces.
Another possible reason - I have heard of having all inbound traffic on one interface and all outbound on another (don't remember why)

Example 3: /etc/hosts file:
192.168.0.1 cheetah.bigcats.com cheetah giga
192.168.0.2 cheetah.bigcats.com cheetah hundred

Setting both to cheetah.bigcats.com - why? I could see if they were set up as giga-cheetah.bigcats.com and hundred-cheetah.bigcats.com, but they should not have the same name - can't think of a reason to do that.

Just expansion

Example 1

Could be differnt levels of access through a firewall, A machine running multiple websites with resolution on ip rather than name

Example 2

Firewall! Bridge! router! the other thing is that in some cases it can be usefull to run different applications on different interfases (e.g. back-up on one, everything else on another).

Example3

Could be that for certain applications you want to load balance or select a specific interface, but for others you dont care OR the machine is acting as a firewall/bridge/router between networks and you want to access it via the same way in both networks, the slight difference would enable routing between the interfaces.

OK thanks for your input.

I assumed this is not the correct way, but the current tcp/ip stacks don't seem to have a problem with it.

In early Unix versions I was told this was not correct but exactly reason and background was I don't know.
I was thinking along the line of a common broadcast address and the system was confused. But the MAC address can be faked so this might be the explanation of why it is possible today.
Cheers
R