Which of the following systems would MOST likely be found in a screened subnet
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A screened subnet is a protective method used in computer networks that have both public and private areas. These systems separate public and private functions into two distinct areas. The local intranet contains the network’s private computers and systems, while the subnet has all the public functions like webservers or public file storage. When information comes from the Internet, the router determines which section of the system it has access to and sends it off accordingly. This is in contrast to a typical network where there is only the intranet on one side of the router and the Internet on the other. Show
In a standard network, a local intranet connects to a router, which directs information outwards to the full Internet. Either within the router or connected to the router is a firewall that protects the intranet from outside interference. With a screened subnet, there is a third portion that is accessible through the router, but not connected directly to the local intranet, that allows access via the Internet. This third section is typically in a demilitarized zone (DMZ), a networking term that means it is not fully protected by the network’s security. One of the basic distinctions in a screened subnet is the difference between private and public systems. A private system contains personal computers, workstations, gaming consoles and other things used by the owners of the network. The public section contains access points that are used by people outside of the network. Common uses for outside connections would be hosting a webpage or file server. Is Amazon actually giving you the best price? This little known plugin reveals the answer. The public areas of the network are fully accessible and visible from the Internet, while the private information is not. Typically, this is accomplished through the use of a three-port firewall or router. One port connects to the Internet and is used by all incoming and outgoing traffic. The second connects only to the public portions of the system while the third connects only to the private. The use of a screened subnet is basically a security feature for the network. In a typical outside attack, the router and firewall would be probed for weakness. Should one be found, the intruder would enter the network and have full access to the intranet. With the use of a screened subnet, the intruder would be most likely to find the public access points and invade the public section only. When a DMZ is in effect, the public protections are much weaker, making it even more likely that that section of the system would be attacked and the private section would be left alone. The architecture of a screened subnet: a screened router separates the external network (Internet) from the bastion hosts in the DMZ, and another screened router defines the internal network. In network security a screened subnet refers to the use of one or more logical screening routers as a firewall to define three separate subnets: an external router (sometimes called an access router), that separates the external network from a perimeter network, and an internal router (sometimes called a choke router) that separates the perimeter network from the internal network. The perimeter network, also called a border network or demilitarized zone (DMZ), is intended for hosting servers (sometimes called bastion hosts) that are accessible from or have access to both the internal and external networks.[1][2][3] The purpose of a screened subnet or DMZ is to establish a network with heightened security that is situated between an external and presumed hostile network, such as the Internet or an extranet, and an internal network. A screened subnet is an essential concept for e-commerce or any entity that has a presence in the World Wide Web or is using electronic payment systems or other network services because of the prevalence of hackers, advanced persistent threats, computer worms, botnets, and other threats to networked information systems. Physical separation of routers[edit]Diagram of a screened subnet using dual firewall devices. Diagram of a screened subnet using a single firewall device. By separating the firewall system into two separate component routers it achieves greater potential throughput by reducing the computational load of each router. As each component router of the screened subnet firewall needs to implement only one general task, each router has a less complex configuration. A screened subnet or DMZ can also be achieved by a single firewall device with three network interfaces.[4] Relationship to DMZ[edit]The term demilitarized zone in military context refers to an area in which treaties or agreements between contending groups forbid military installations and activities, often along an established frontier or boundary between two or more military powers or alliances. The similarity to network security is that the screened network (DMZ) has reduced fortifications because it has intended points of ingress from the external network which is presumed to be hostile. It appears that the term demilitarized zone (DMZ) was popularized as a sales and marketing term sometime after the development of screened routers and firewalls. It is often used as a synonym but may have once had a different meaning. "There are a number of terms that are used, such as bastion hosts, screened subnets, DMZ, or perimeter networks that can be confusing, especially when used together." ... "Another term that may often causes confusion is the DMZ (demilitarized zone), as opposed to a screened subnet. A true DMZ is a network that contains hosts accessible from the internet with only the exterior, or boarder, router between them. These hosts are not protected by a screening router." ... "A screened subnet may also be a collection of hosts on a subnet, but these are located behind a screening router. The term DMZ may be used by a vendor to mean either, so it is best to verify which they mean."[5]Comparison to screened host firewall / architecture[edit]Whereas the screened subnet firewall employs two screened routers to create three subnets, a screened host firewall employs only one screened router to define two subnets: an external network and an internal network.[6][7][8] The screened subnet firewall is more secure because an intruder must traverse two filtered routes to reach the internal network. If the bastion / DMZ host is compromised the intruder must still bypass the second filtered route to reach internal network hosts. What does a screened subnet create?A screened subnet, or triple-homed firewall, refers to a network architecture where a single firewall is used with three network interfaces. It provides additional protection from outside cyber attacks by adding a perimeter network to isolate or separate the internal network from the public-facing internet.
Is the DMZ a screened subnet?The purpose of a screened subnet or DMZ is to establish a network with heightened security that is situated between an external and presumed hostile network, such as the Internet or an extranet, and an internal network.
What is the different variants of a screened subnet firewall?Screened host firewalls:
There are two types of screened host-one is single homed bastion host and the other one is dual homed bastion host. In case of single homed bastion host the firewall system consists of a packet filtering router and a bastion host.
What are the functions of the two firewalls in a screened subnet?A screened subnet uses two firewalls. The external firewall is connected to the internet and allows access to public resources. The internal firewall connects the screened subnet to the private network.
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