$1.$ Define fragmentation and reassembly in the context of IP addressing, highlighting the scenarios in which fragmentation occurs and the purpose of reassembly at the receiving host. $2.$ Discuss the conditions under which fragmentation occurs in a router, emphasizing the relationship between the size of the datagram and the MTU of the network it is forwarded over. $3.$ Explain the role of the Ident field in the fragmentation process and its significance in reassembly at the receiving host. How does IP ensure that all fragments belonging to the same datagram are correctly identified and reassembled? $4.$ Describe the characteristics of fragments as self$-$contained datagrams and explain why IP does not recover from missing fragments. How does this impact the reliability of data transmission over IP networks? $5.$ Provide a scenario illustrating the fragmentation and reassembly process for a datagram that exceeds the MTU of an Ethernet network $(1500$ bytes$).$ Include details such as the size of the datagram, the number and size of fragments generated, and the reassembly process at the receiving host.