Compare TACACS+ and RADIUS with regard to strength of security.

What will be an ideal response?

TACACS+ provides stronger security than RADIUS. For example, the Transmission Control Protocol (TCP) is considered more secure than User Datagram Protocol (UDP), an alternative network communications protocol, because when a host sends a TCP packet, it expects a packet to be sent in response with the ACK bit sent to show that a connection has been established. ACK (for "acknowledgement"), is one of the flags in the TCP header part of a packet, and it indicates that the destination computer has received the packets that were previously sent. UDP, in contrast, is considered "connectionless." If a UDP packet is sent, an acknowledgement packet is not sent. If the destination host doesn't receive the packet, it simply asks for the packet to be resent.