What is lmhosts?

What is lmhosts?

Lmhosts is a text file used in Microsoft Windows operating systems to map network basic input/output system (NetBIOS) names to internet protocol (IP) addresses on a local network. It stands for local area network (LAN) Manager Hosts, and it provides a way to resolve NetBIOS names to IP addresses without relying solely on domain name system (DNS). The lmhosts file is located in the Windows\System32\Drivers\Etc directory.

How does lmhosts work?

When a computer wants to communicate with another computer on the same network using its network basic input/output system (NetBIOS) name (e.g., COMPUTER1), it first checks the lmhosts file for a corresponding internet protocol (IP) address. If a match is found, the IP address is used to establish the connection. If no match is found, the computer will resort to other methods like domain name system (DNS) resolution or broadcast requests.

Why would I need to use lmhosts?

The main use case for lmhosts is in situations where domain name system (DNS) is not available or doesn't support network basic input/output system (NetBIOS) name resolution. It can be particularly useful in older Windows environments or in scenarios where legacy applications rely on NetBIOS. Lmhosts allows you to manually configure mappings between NetBIOS names and IP addresses, ensuring that communication can occur even without DNS.

How do I create a lmhosts file?

To create a lmhosts file, you can use any text editor such as Notepad. Open a new file and save it with the name "LMHOSTS" (without any file extension). The file should be saved in the Windows\System32\Drivers\Etc directory. Each entry in the lmhosts file consists of a network basic input/output system (NetBIOS) name, its corresponding IP address, and optional comments. The format is as follows:

IP_address    NetBIOS_name   #optional_comment

For example:

192.168.1.10 COMPUTER1

How do I enable lmhosts lookup on my computer?

To enable lmhosts lookup on your computer, you need to ensure that the " lmhosts Lookup" option is enabled in the network adapter settings. Here's how you can do it:

1. Go to the Control Panel and open the "Network Connections" or "Network and Sharing Center" (depending on your Windows version).
2. Right-click on your network adapter and select "Properties."
3. Scroll down and find the "Internet Protocol Version 4 (TCP/IPv4)" entry.
4. Click on "Properties."
5. In the new window, click on the "Advanced" button.
6. Go to the "WINS" tab.
7. Check the box that says "Enable LMHOSTS lookup" or a similar option.
8. Click "OK" to save the changes.

Can I use wildcards in the lmhosts file?

Yes, you can use wildcards in the lmhosts file to specify multiple NetBIOS names with a single entry. The asterisk (*) character acts as a wildcard and matches any characters. For example, if you want to map all NetBIOS names starting with "COMP" to the same IP address, you can use the following entry:

192.168.1.10    COMP*   #Mapping for multiple computers

This will match names like COMPUTER1, COMPUTER2, and so on.

What happens if there is a conflict between entries in the lmhosts file and domain name system (DNS)?

When a conflict occurs between entries in the lmhosts file and DNS, the lmhosts file takes precedence. This means that if there is a matching entry in the lmhosts file for a network basic input/output system (NetBIOS) name, the IP address specified in the lmhosts file will be used, ignoring the DNS resolution.

Can I use lmhosts to resolve names in different subnets?

Lmhosts is primarily used for local network name resolution and may not work across different subnets without additional configuration. To resolve names in different subnets, you would typically need to rely on domain name system (DNS) or windows internet name service (WINS).

Is lmhosts still relevant in modern networks?

While lmhosts has been largely superseded by domain name system (DNS) and other modern name resolution methods, it can still be useful in certain scenarios. Legacy applications or environments that rely heavily on network basic input/output system (NetBIOS) may benefit from using lmhosts in conjunction with other methods. However, in most modern networks, DNS is the preferred method for name resolution.

Can I use lmhosts on non-Windows operating systems?

Lmhosts is a feature specific to Windows operating systems and is not natively supported on non-Windows platforms. However, there are alternative methods available for name resolution on other operating systems. For example, on Unix-based systems, you can modify the hosts file located in the /etc directory to manually map IP addresses to hostnames.

Does lmhosts support dynamic updates?

No, lmhosts does not support dynamic updates. Unlike domain name system (DNS), which can dynamically update its records when IP addresses change or new devices join the network, lmhosts requires manual modification of the file whenever changes occur.

Can I use lmhosts in a domain environment?

Lmhosts can be used in a domain environment, but it is not the recommended method for name resolution within a domain. In a domain, it is preferable to rely on Active Directory and domain name system (DNS) for name resolution. These technologies provide more robust and scalable solutions for managing hostnames and internet protocol (IP) addresses.

What is the purpose of lmhosts in Windows networking?

Lmhosts is a text file used by Windows operating systems to map network basic input/output system (NetBIOS) names to internet protocol (IP) addresses. It provides a way to resolve network names without relying solely on DNS.

Can lmhosts be used for name resolution on the internet?

No, lmhosts is primarily designed for resolving NetBIOS names within local networks and is not intended for use on the internet.

What is the process of updating lmhosts across multiple computers in a network?

To update lmhosts across multiple computers, you can use Group Policy or logon scripts to distribute the updated lmhosts file to all the relevant machines.

Can I specify multiple internet protocol (IP) addresses for a single network basic input/output system (NetBIOS) name in lmhosts?

No, lmhosts only supports mapping a NetBIOS name to a single IP address. You would need to create separate entries for each IP address.

Does lmhosts provide any caching mechanism for name resolution?

No, lmhosts does not incorporate a caching mechanism. Each time a name resolution request is made, the lmhosts file is read.