Exam JN0-335 Topic 4 Question 64 Discussion

Explanation
The DNS ALG is an application layer gateway that handles data associated with locating and translating domain names into IP addresses.
The DNS ALG supports the following features:
DDNS: The DNS ALG supports dynamic DNS (DDNS), which allows hosts to update their DNS records dynamically when their IP addresses change.
The DNS ALG monitors the DDNS update messages and performs the necessary address transformations2 DNS doctoring: The DNS ALG performs DNS doctoring, which is a process of modifying the DNS responses to match the NAT address translation. This is done to resolve the problems introduced by NAT, such as the mismatch between the internal and external IP addresses of a host. The DNS ALG performs the IPv4 and IPv6 address transformations for both DNS and DDNS responses2 The DNS ALG does not support VPN tunnels or NAT itself. The DNS ALG works with NAT, but does not perform NAT. The DNS ALG only supports UDP traffic, not TCP traffic2 References:
1: Juniper Security Specialist (JNCIS-SEC) (JN0-334) | Study Guide 3
2: Junos OS Security Configuration Guide | DNS ALG 1