Name Resolution with the DNS:
Computers on TCP/IP networks are assigned both a host name and an IP address. Users generally access systems by their descriptive names, and the network needs to translate, or resolve, those names into the relevant systems’ IP addresses. The Domain Name System (DNS) is the primary name resolution service on the Internet as well as private IP networks.
DNS is a hierarchical system of databases that map computer names to their associated IP addresses. DNS servers store, maintain, and update the databases and respond to DNS client name resolution requests to translate host names to IP addresses. The DNS servers on the Internet work together to provide global name resolution for all Internet hosts.
Another way to resolve machine names to IP addresses is to provide each computer on the TCP/IP network with a hosts ﬁle. The hosts ﬁle is a text ﬁle that contains a list of computer names and their associated IP addresses. The use of hosts ﬁles predated the development of DNS and they are no longer commonly used, because this manual name-resolution method is practical only on very small and very stable networks. Adding a new computer, for example, requires that the hosts ﬁle of every computer that might need to reach it be manually updated with the new information.
However, a TCP/IP system will still use entries in the hosts ﬁle if the ﬁle is present, and the hosts ﬁle actually takes precedence over DNS name resolution. This can make the hosts ﬁle useful for testing purposes. However, if the hosts ﬁle is conﬁgured incorrectly, it can cause connectivity problems even when the DNS conﬁguration is correct. Because altering the hosts ﬁle is a simple way to disrupt communications, the hosts ﬁle can be a target of attacks or malware. Be sure to check it when you troubleshoot name resolution and connectivity.
On Windows systems, the hosts ﬁle is stored in C:\WINDOWS\System32\drivers\etc. The default ﬁle contains only commentary and an entry for the localhost address, but you can edit the ﬁle to add additional entries if needed.
The Windows Internet Name Service (WINS) is Microsoft®’s NetBIOS name resolution service, which was developed to reduce the number of NetBIOS name resolution broadcasts on networks that use NetBIOS naming. The WINS server uses a name resolution table to map NetBIOS names to protocol addresses. WINS clients are conﬁgured with the IP address of the WINS server so that they automatically register their names in the WINS database when they come online. They can also resolve names by targeted requests to the WINS server.
There has been talk of phasing out WINS for years, and Microsoft began to move in that direction with the release of Windows Server 2008. The WINS server service is replaced in Windows Server®2008 with a new type of DNS zone that will still sup-port older WINS clients.