Network Services Server
DNS: The Domain Name System (DNS) is a central part of the Internet, providing a way to match names (a website you're seeking) to numbers (the numeric address for the website). Anything connected to the Internet - laptops, tablets, mobile phones, servers hosting your websites - has an Internet Protocol (IP) address made up of numbers. Your website might have an IP address like 126.96.36.199, but this is obviously not easy to remember. However a domain name such as mywebsite.com is something people can recognize and remember. DNS syncs up domain names with IP addresses enabling humans to use memorable domain names while computers on the Internet can use IP addresses. Hostnames in TCP/IP based network are resolved either with a static HOSTS file on your PC or from a DNS service (usually offered by your Internet Service Provide).
WINS: WINS is used for NetBIOS name resolution. WINS, LMHOSTS is used for resolution of NetBIOS names to IP addresses. NetBIOS names is based on an older protocol and should be used within a LAN only and registers itself on that network Windows Internet Name Service (WINS) is more than just an IP address resolver. It enables centralized management of NetBIOS namespace data and eliminates the need to remotely manage multiple LMHOSTS files (which perform the same function for NetBIOS lookup that Hosts file perform for DNS lookup). Everytime that PC is powered up or rebooted using LMHOSTS, broadcasts or WINS to provide resolution of a NetBIOS hostname to it's IP address. NetBIOS names are limited to 16 characters in length with 15 characters visible.
DHCP: Dynamic Host Configuration Protocol (DHCP) is a network protocol that enables a server to automatically assign an IP address to a computer from a defined range of numbers (i.e. a scope) configured for a given network. DHCP leases IP addresses and other parameters like subnet mask, default gateway to client computers dynamically. You have to assign the IP address for your DHCP server statically. A DHCP server can't assign an IP address to itself. Similarly, some other Servers which need static assignment of IP addresses are your DNS server, WINS server, Default gateway.
Some important point to remember:
Mail Server: Mail servers serve as an outbound client and inbound retrieval server for electronic messages, commonly via the STMP (simple mail transfer) protocol. Microsoft Exchange servers are the most common form of mail servers.
Remote Access Server (RAS): RAS is a type of server that provides a suite of services to remotely connected users over a network or the Internet. It operates as a remote gateway or central server that connects remote users with an organization's internal local area network (LAN). Once connected with a RAS, a user can access his or her data, desktop, application, print and/or other supported services.
Having a dedicated server for a specific purpose can speed up processing times and ensure sufficient resources are available during peak volumes. If the load on any specific server is not high, then you may consider installing two or more servers on the same physical computer.
Application server: Application servers can power shared apps, games, output from scripts and programs as well as serving data from an API (application protocol interface.) Modern application servers are optimized for load balancing and are often located in a cloud, which enables them to distribute data more efficiently.
File server: File servers can store a variety of media for distribution, including movies, audio and animation, rendering media at high speeds to client machines for games, movies and other forms of applications.
Directory Services Server: A Directory Services Server verifies the credentials of users and authenticates them. In addition, it also provides them with access to resources using single sign-on (SSO). SSO allows users to authenticate once and not be required to authenticate again to access the resources to which they have been given access.
Database server: Database servers manage data with the help of specialized software such as "SQL Server" or MySQL server. When you have large amount of queries, and a large amount of data to be parsed, you may need a dedicated database server with appropriate hardware resources such as memory, CPU, and disk capacity.