# High Availability with Single-hop or Double-hop DMZ Many companies use the perimeter network (DMZ) to separate the public network with servers that handle exposed services and the internal network with servers that handle internal services. There are two types of DMZ: single-hop and double-hop, with the latter using three firewalls and therefore being more expensive, but more secure (with three firewalls, using different firewall technologies, you can avoid one weakness or one type of attack breaking all firewalls). A firewall between RAS Secure Gateways and the intranet must allow gateways and systems to connect to a RAS Connection Broker using the standard port. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.parallels.com/landing/ras-reference-architecture/v20/deployment-scenarios/parallels-ras-deployment-scenarios/high-availability-with-single-hop-or-double-hop-dmz.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.