Comprehensive and Detailed Explanation:
If aping to 10.0.100.19 is unreachable, themost likely issueis that users areon the wrong subnetand cannot communicate with the server.
Breakdown of Options:
* A. The users are on the wrong subnet.#Correct answer.If users are ona different subnetwithout proper routing,they won't reach the server.
* B. The DHCP server renewed the lease.- Wouldchange the client'sIP, but the server'sstatic IP should remain unchanged.
* C. The IP address was not reserved.- DHCP reservations matter fordynamic IPs, but RDP servers typically have static IPs.
* D. The hostname was changed.- Would affectDNS resolution, butpinging the IP directly would still work.