In the context of Microsoft's Active Directory (AD), a "Site" does not precisely equate to an Internet Protocol (IP) subnet, although there is an interplay between the two concepts. Active Directory "Sites" are logical entities used in the service to delineate network infrastructure for the purposes of administration and replication. Sites are a representation of the physical structure of your network and can be composed of one or more IP subnets.
An Active Directory Site is usually composed of networks that are well-connected in terms of speed and reliability. They generally comprise of LAN segments rather than slower WAN links. When you establish multiple sites, Active Directory can optimize network traffic, ensuring that resources are used most effectively and providing a more efficient replication mechanism.
While a site could technically be constructed of one subnet, it's not necessary to do so; you can have multiple subnets within one site. The key here is that communication within a site should be high-speed and reliable, often reflecting a geographical location or a specific part of your organizational infrastructure. Therefore, you are correct in stating that a site could contain two or more subnets connected by a high-bandwidth link, but it's important to understand that the concept of an Active Directory Site is not strictly tied to the notion of a subnet. It's a higher-level, more flexible construct designed to help structure and optimize network communication within the constraints of your physical infrastructure.
'Site' is defined as a set of IP Subnets
In Active Directory, a 'Site' is defined as a set of IP subnets that have high-speed and reliable network connections among them.
A Site can consist of one or more IP subnets, but it is not limited to one subnet, and it does not equate directly to a subnet. It is designed to facilitate efficient traffic flow and replication among different parts of an organization's network infrastructure.
The configuration of 'Sites' in Active Directory is primarily used to control replication traffic, authenticate users to the nearest domain controller, and facilitate resource localization in larger network environments. It allows administrators to align Active Directory with the physical topology of their network for optimization and performance enhancement.
So, while 'Sites' and subnets are related concepts in Active Directory and network architecture, a 'Site' is not an IP subnet. It's a higher-level construct designed to encompass one or more subnets to optimize network performance and manageability.
Sites are used to control network traffic related to logon authentication and Active Directory replication.
As an administrator, you may need to create multiple sites if your network is large and geographically dispersed. Creating sites isn't something that is done frequently, or at all with smaller networks. With a large network, sites are created when you initially set up the Win2000 network. If you added a new branch office in a new location you might create more sites.
How to create a 'Site'
Creating a site involves providing a name for the new site and associating the site with a site link. You must either log on as a member of the Enterprise Admins group to create sites or use the Secondary Logon Service to start Active Directory Sites and Services in the security context of a member of the Enterprise Admins group. Once in Sites and Services, you must complete these steps:
Open Active Directory Sites and Services from the Administrative Tools menu.
In the console tree of Active Directory Sites and Services, right-click Sites, and then click New Site.
In the Create New Object - (Site) dialog box, type a site name in the Name box.
Click a site link, and then click OK. (Select the default site link if it is the only link available.)
Create AD Site (Steps)
Having clicked Start, you willl need to choose the Administrative Tools menu from Programs.
With the Administrative Tools menu now opened, select Active Directory Sites and Services.
The Active Directory Sites and Services box appears. In the console tree, right-click Sites.
Now select New Site
In the Create New Object - (Site) dialog box, type a site name in the Name box. For this simulation, type "MySite."
Then click a site link from the list of link names.
A dialog box explaining how to complete the configuration appears. Click OK.
MySite now appears in the Active Directory Sites and Services console. This completes the Simulation. Click the Exit button.