Answer:
Check the explanation
Step-by-step explanation:
For 1st part (which you said not needed):
Layers that are most likely concerned:
1- A computer will not connect to the net. After some investigation you will then discover that the patch cable is note ended properly.
2- A computer can access resources on the local LAN but not on a unlike subnet. You find that the computer’s default gateway is not configures properly.
3- You can ping a computer that you are trying to transport files to via FTP, but you can’t communicate via FTP.
4- All computers associated to a particular hub have lost network connectivity. You determine that the hub is the trouble.
5- You get an encrypted text file, but when you open it, you will then discover the text is unreadable. You decide that decryption did not take place as it should have.
For 2nd part of your question::
This is a some sort of answer and may not helpful always.............................
As we know dynamic addresses are popular with ISP, because it enables them to use fewer IP addresses than their total figure of customers.
They only need an address for each customer who is active at any one time. Globally routable IP addresses cost money, and some establishment that specialize in the obligation of addresses (such as RIPE, the European RIR) are very strict on IP address usage for ISP's(Internet service providers). Assigning addresses dynamically allows ISPs(Internet service providers) to save money, and they will often charge extra to provide a static IP address to their customers