3.4 Implement a NetBIOS naming scheme for all computers on a given network.
NetBIOS name provides flat name spaces, which means that all names within a network must be unique. NetBIOS names are 16 characters in length. Resources are identified by NetBIOS names that are registered dynamically: when computers and/or services start or when users log on.
Names can be registered as unique (one owner) or as group (multiple owners) names. NetBIOS names can be used to identify a unique computer or a special group of computers. NetBIOS names are 16 characters in length. The user or administrator can specify the first 15 characters of a NetBIOS name, but the 16th character of the NetBIOS name is used to indicate a resource type (00-FF hex).
You can use nbtstat command use to obtain information about NetBIOS names. For example, when user "ww" login the computer name "mulan" in the "CAT" domain, you will see the following output when you use nbtstat -n command.
Here "mulan" is the primary domain controller of "cat" domain running Windows NT Server with Internet Information Server.
In the above diagram, there are two parts in a NetBIOS name. The first part has 15 characters such as "IS~MULAN .". Please note "MULAN" also has 15 characters because you need to add ten space characters on it. As such, the first part of NetBIOS name always has 15 characters. There is only one character on the second part. It is shown in hex number such as <1F>, <00> in the system.
Some typical usage of NetBIOS name is as following:
Redirector = COMPUTERNAME + <00h>
Messenger = COMPUTERNAME + <03h>
Server = COMPUTERNAME + <20h>
There are two types of NetBIOS name: UNIQUE and GROUP.
TCP/IP uses a different addressing mechanism than NetBIOS for identifying a process on the network. Therefore, when a NetBIOS communication request is handed to TCP/IP, it must convert the NetBIOS addressing scheme into the address format it understands. TCP/IP does this by associating the NetBIOS name with the IP address of the computer containing the process with the specified NetBIOS name. The process of mapping a NetBIOS name to an IP address is called NetBIOS Name Resolution.
If you dont have a manual on hand, it is hard to know the exact meaning of a NetBIOS name. You may read everything you can access regarding the NetBIOS name and still you have no idea on how to answer FTQ 3.4.2. To prepare for the Networking Essentials exam, we will try to learn as much as possible. However, sometimes we may be unable to understand some questions in the exam. In such an event, it is recommended to read the questions carefully.
In FTQ 3.4.2, you have to choose three of four possible answers. Since one of the answers is wrong, it may be easy to determine which one is wrong answer.
Lets review the purpose of NetBIOS name first. As previously mentioned, NetBIOS names can be used to identify a unique computer or a special group of computers. The main point here is that NetBIOS is used to identify a computer or a special group of computers. Lets look at the possible answers of FTQ 3.4.2 to see which one belongs to computer or a special group of computers. A computer name is for a computer; without doubt, it can be used to distinguish from one NetBIOS name to another. A domain has lots of computer inside, and we can consider it as a special group of computers. Therefore, domain name also works to prevent NetBIOS name duplicated. Same thing is true for workgroup name. "Shared resource name" has nothing to do with a unique computer or a special group of computers. So choose D, it is the only one among the possible answers that is wrong.
DHCP: Dynamic Host Configuration Protocol offers dynamic configuration of IP addresses and related information. DHCP provides simple TCP/IP network configuration, prevents address conflicts, and helps conserve the use of IP addresses through centralized management of address allocation. In a DHCP server, you just need to setup a TCP/IP address pool. After that, whenever a DHCP enabled client connect to the network, it will contact DHCP server and choose an unused IP from the IP address pool.
The DHCP provides the following benefits: 1) You dont need to assign an IP address to each machine wired to the network. 2) If you want to move one computer from one network to another and both networks have the DHCP server installed, it minimizes the effort for the configuration. Newer DHCP servers dynamically update the DNS servers after making assignments.
DNS: Domain Name System provides the user-friendly name for the TCP/IP addresses. A DNS server maintains a database of domain names (host names) and their corresponding IP addresses. Try the following command in DOS command when you are connecting the Internet.
Ping www.yahoo.com
You will see something like this:
You will know the yahoos IP address is 204.71.177.70. You can always type http://204.71.177.70 to go to yahoos homepage. This is a tedious work. Everybody would prefer to type http://www.yahoo.com instead of http://204.71.177.70. You can also imagine that in yahoos DNS server, there is a line mapping the IP address 204.71.177.70 to www.yahoo.com.
WINS (Windows Internet Naming Service) also maintains a database of computer names and their physical IP address like DNS. However, Unlike DNS server can be NT or UNIX, WINS only runs on Windows NT system. WINS maps the host name to the IP address. When a computer is moved to another subnet and a new IP address is assigned by DHCP, the WINS database is updated. Please note WINS also works in a routable environment, you can only have one WINS over WAN links.
You can also use a text file such as LMHOSTS and HOSTS (You can find these two files at \%WindowsNTroot\system32\drivers\etc\ directory) to synchronize the computer name to the IP address. LMHOSTS file provides equivalent function as a WINS server and HOSTS file provides equivalent function as a DNS server.
UNC means universal naming convention. UNC name is of \\servername\sharename syntax. The server name is the computer server's name and the share name is the name of shared resource. You can also include the directory path in the share name with the following syntax:
\\servername\sharename\directory\filename
LMHOSTS is always correct to resolve computer names. In fact, you can always put the LMHOSTS file in a computer for name resolution. Both NDS and WINS server can resolve the names. But DNS corresponds to the HOSTS file and WINS corresponds to the LMHOSTS file. Therefore, CD is correct.