Cisco Certified Internetwork Expert (CCIE) Practice Test

In which scenario would DTLS be the appropriate choice?

1. For large data transfers over TCP

2. When using reliable transmission protocols

3. For real-time applications requiring security

4. In cases where TCP has limitations due to firewalls

The correct answer is: For real-time applications requiring security

DTLS, or Datagram Transport Layer Security, is specifically designed to provide security for datagram-based applications that require low latency and real-time communication. This makes it an ideal choice for scenarios such as voice over IP (VoIP), video conferencing, or online gaming, where the timely delivery of packets is critical and delays introduced by retransmission (as seen in TCP) can negatively impact the user experience. The use of DTLS allows these real-time applications to maintain a level of security comparable to TLS (which operates over TCP) but without the added overhead and delay that comes with establishing and maintaining a TCP connection. Rather than ensuring messages are delivered in order and managing retransmissions like TCP, DTLS allows for packets to be sent more freely, with the understanding that some may be lost in transit but security is still upheld. In contrast, scenarios involving large data transfers typically benefit more from the reliability of TCP rather than the efficiency of UDP (which DTLS uses). Reliable transmission protocols impose additional requirements that DTLS is not designed to handle, as they focus on ensuring all data is received correctly, which is contrary to the low-latency model of DTLS. Additionally, while it is true that TCP can face challenges with firewalls, DTLS is