22. Troubleshooting Your Network
When Good Networks Go Bad
As part of my software consulting work, I end up doing a fair bit of network support for my clients. And every time I get a call from a client with a network problem, I cringe. I never know whether it’s going to take 10 minutes or a week to fix. Sometimes the problem isn’t so bad; I’ve fixed more than one “broken” computer by simply plugging it in. If such an easy fix doesn’t present itself immediately, though, a bit of a cold sweat breaks out on my forehead. The problem could be anything. How do you even start to find a nasty problem in the maze of cards, wires, drivers, and hidden, inexplicable system services? And it’s difficult enough debugging the stuff that belongs there. What if viruses, adware, or rootkits are messing up the works?
Well, if you work for a corporation with a network support staff, of course, the answer to any of these questions is to call the help desk and then take a refreshing walk around the block while someone else sweats over your network. It’s great if you can get that kind of support. If you want to (or have to) go it alone, though, the good news is that some tools provided with Windows can help you find the problem. After discussing troubleshooting in general, this chapter shows you how to use these tools.
In reading this chapter, you probably won’t find the solution to any particular network problem you’re having. I can’t really help you solve any one specific problem here, but I can show you some of the tools available to help you identify the source of a problem you might have.
Getting Started
In years of helping clients and friends with hardware, software, and network problems, what I’ve noticed is that the most common—and most frustrating—way people report a problem is to say “I can’t...” or “The computer won’t....” Unfortunately, knowing what doesn’t happen isn’t helpful; after all, at any given time, there is an infinite number of things that aren’t happening. I always have to ask, “What does happen when you try?” The answer to that question usually gets me well on the way to solving the problem. The original report usually leaves out important error messages and symptoms that can identify the problem. If you can get someone to express a problem in terms of what is happening, rather than what isn’t, you’ll go from “My online banking doesn’t work” to something like “The website says my password is invalid” or “Windows says that I don’t have any network connections.” This leads from the vague toward something you can grapple with.
Extending that principle, as you work on a problem, pay as much attention to what does work as to what doesn’t. Knowing what isn’t broken lets you eliminate whole categories of problems. For example, check to see whether a problem affects just one computer or all the computers on your home or office network. If other computers can manage the task that one computer is having trouble with, you know that the problem is located in that one computer, or in its connection to the others.
The following are some other questions I always ask:
Does the problem occur all the time or just sometimes?
Can you reproduce the problem consistently? If you can define a step-by-step procedure to reproduce the problem, can you reduce it to the shortest, most direct procedure possible?
Has the system ever worked, even once? If so, when did it stop working, and what happened just before that? What changed?
These questions can help you determine whether the problem is fundamental (for example, due to a nonfunctioning router) or interactive (that is, due to a conflict with other users, with new software, or confined to a particular subsystem of the network). You might be able to spot the problem right off the bat if you look at the scene this way. If you can’t, you can use some tools to help narrow down the problem.
Generally, network problems fall into one or more of these categories:
Application software
Network clients
Name-resolving services
Network protocols
Addressing and network configuration
Driver software
Network cards and hardware configuration
Wiring/hubs/Wi-Fi connectivity
Internet connectivity
If you can determine which category a problem falls in, you’re halfway to finding the culprit. At that point, diagnostic tools and good, old-fashioned deductive reasoning come into play. (That, and random plugging and unplugging of things.)
Tip
You might also peruse Chapter 17, “Troubleshooting an Internet Connection,” for tips on diagnosing network problems specific to the Internet (TCP/IP) protocol, the router, and Internet connectivity.
You might be able to eliminate one or more categories right away. For example, if your computer can communicate with some other computers but not all of them, and your network uses a central hub, you can deduce that at least your computer’s network card and the wiring from your computer to the hub are working properly.
Windows comes with some diagnostic tools to help you narrow down further the cause of a network problem. The following sections outline these tools and suggest how to use them.
Using Troubleshooters and Diagnostic Tools
Each diagnostic tool described in this section serves to test the operation of one or more of the categories mentioned in the preceding section. The tools are discussed in roughly the order you should try them.
Some tools can be used to find problems in any of the many networking components. These tools quickly identify many problems.
The Network and Sharing Center
The Network and Sharing Center is the first place to start diagnosing a network problem because it can quickly take you to Windows network troubleshooters, status displays, and network settings. There are several ways to bring up the Network and Sharing Center. Here are two easy ways:
Right-click the small network icon located in the notification area on the taskbar, near the clock. Select Open Network and Sharing Center.
In the taskbar’s Search box, type the word sharing. Select Network and Sharing Center from the search results.
Either method brings up the window shown in Figure 22.1.
Figure 22.1 The Network and Sharing Center gives you a quick overview of your network and Internet status and leads to other diagnostic and setup tools.
Under View Your Active Networks, Windows displays information about any active network and/or direct Internet connections. For example, in Figure 22.1, you can see that I am attached to a LAN through the network adapter named Ethernet. The network location is set to Private, which means that file and printer sharing are allowed. The network can reach the Internet, and the computer is a member of a homegroup.
If you want to use file sharing and/or the HomeGroup feature, your network location must be “Private Network.” For more information, see “Setting Up a Homegroup,” p. 406.
This window leads to several other useful tools:
To see whether various networking features are turned on or off, click Change Advanced Sharing Settings.
To let Windows try to diagnose your network problem, click Troubleshoot Problems. Then select a troubleshooter for the particular problem you’re having (see “Network Troubleshooters,” later in the chapter, for a description of these tools).
To check or modify the settings for one of your network adapters, click Change Adapter Settings.
To check or change your homegroup settings, click HomeGroup in the lower-left portion of the window.
To see whether your computer can find other computers on your network, click Network and Internet in the Windows address bar, at the top of the window; then click View Network Computers and Devices. We discuss this next.
If you’re having problems with file and printer sharing, the first thing to check is the Network window.
Network
The Network window lets you determine whether your computer can “see” other computers on your network that are sharing files, printers, or media. Use any of these methods to view the Network window:
From the desktop, click the File Explorer icon pinned to the taskbar. Then click Network in the Navigation pane at the left.
In the taskbar’s search box, type view network, and then select View Network Computers and Devices from the search results.
Press Windows Logo+X and select Control Panel. Click Network and Internet. Then click View Network Computers and Devices.
Note
Other computers will appear only if your Network Location setting is Private Network, which is set in the Network and Sharing Center window. Otherwise, file and printer sharing is disabled.
The window that appears should look something like Figure 22.2, except that the names of the computers on your network will be different.
If you see at least one other computer besides your own displayed here, your computer’s network cabling, network adapter, and drivers are working correctly. In addition, both your computer and the computers shown are running the Network Discovery service and/or file sharing.
If other computers don’t appear, check the following:
If your network is protected from the Internet by a firewall or a router, be sure that the Network Location is shown as Private Network. Check the Network and Sharing Center, as discussed in the preceding section. If it’s set to Private, click the Network icon in the taskbar, select Network Settings, click the name of your network connection, and turn on Find Devices and Content.
If your computer is directly connected to the Internet in a public place such as a school or an Internet cafe, it’s not safe to enable file sharing. Your network type must be set to Public, and file sharing should be disabled. Other computers should not appear in the Network list.
For more information, see “Take Care When You Share,” p. 842.
If a computer that you want to connect to is powered up, connected to the network, and is correctly configured but still doesn’t appear in the Network list, try these procedures:
Wait 10 minutes, and then press the F5 key or right-click the window and select Refresh. Other computers might appear this time.
Check each of the computers in your workgroup and make sure that each computer is set to use the same workgroup name and that each computer has the same set of network protocols installed. In particular, any computers running Windows XP or earlier versions must be reconfigured to use only TCP/IP and not IPX/SPX or NetBEUI.
Be sure that other computers’ firewall software is set up to permit file and printer sharing on the local subnet.
Frankly, the software that Windows uses to identify other computers on the local network, called the Browser service, is flaky at best, and sometimes no computers appear in this display even when networking is fine. This can happen if you have more than one physical network (both wireless and Ethernet, for example, or multiple wireless access points), or, for no good reason at all.
For information about networking with older versions of Windows, see Chapter 20, “Networking with Other Operating Systems.”
Tip
Sometimes, add-on software can wreak havoc with networking and especially file sharing. If you install the Cisco VPN Client for work, for example, it might install an unconfigurable firewall component that is turned on all the time, even when you’re not connected through the VPN, and it blocks your computer from sharing files or printers. Nice, huh? If this happens, uninstall the Cisco VPN and run the installer again using the Command Prompt window. Put DONTINSTALLFIREWALL=1 at the end of the command line.
This is just one example of the kind of thing that can happen. If networking suddenly stops working after you’ve installed a program or app, google the program name and see if others have had the same problem.
If you are having trouble with file and printer sharing with some or all of your other computers, and this screen didn’t identify the problem, go back to the Network and Sharing Center and click Change Advanced Sharing Settings. This displays settings that Windows uses with home/work (private) networks and public networks, respectively. The settings are divided into three parts:
Private—Settings used for a network connection that leads to home or office networks. A network can be a home or work network, even if it provides Internet access, as long as a router or firewall is placed between the network and the Internet, and as long as you trust all the computers plugged in to the network.
Guest or Public—Settings used for network connections that lead directly to networks in an insecure environment. A public network could be a direct Internet connection (for example, a connection plugged in directly to a DSL or cable modem) or a network in a public place such as a hotel or cafe, where you do not trust the other computers.
All Networks—Settings used on all network connections. These settings control file-sharing and media-sharing security options.
The first two sections are location-dependent settings, and the settings in the third section are location independent. The default settings are listed in Tables 22.1 and 22.2.
Network Troubleshooters
Windows 10 has a set of network repair tools called troubleshooters that are said (by Microsoft) to be capable of recognizing and diagnosing more than 100 network problems. We’re skeptical of claims like this; but, on the other hand, it takes only a few seconds to let these tools examine your network and offer whatever advice they can, so it’s absolutely worth letting them take a crack at whatever problems you’re experiencing.
There are several different network troubleshooters, each dealing with different categories of problems. You have two ways of getting to them that look very different, but run the same set of tools.
The quickest way to start them is to right-click the network icon at the right end of the taskbar and select Troubleshoot Problems. This method runs some basic network adapter tests, prompts you to select the type of problem you’re experiencing, and then runs the appropriate troubleshooting programs. We won’t describe this further; it’s self-explanatory once you’ve started the process.
You can also access the individual troubleshooters directly: Open the Network and Sharing Center as described earlier in this chapter. Click Troubleshoot Problems. Then select one of the network troubleshooters from the list. Your computer might not show all of these and might have additional troubleshooters to offer.
Internet Connections—Select this option if you are having a problem reaching the Internet in general, or even one particular website.
Shared Folders—Select this option if you can’t access a network shared file or folder whose name you know.
Tip
Whichever troubleshooter(s) you use, if the word Advanced appears on the first screen, click on that word to expose a set of options. Be sure that Apply Repairs Automatically is checked, and then click on Run As Administrator.
HomeGroup—Select this option if you’re having problems accessing a homegroup.
Network Adapter—Select this option if you’re having general problems accessing the Internet and/or network resources and suspect a hardware problem.
Incoming Connections—Select this option if other computers can’t connect to your computer’s shared files or to other programs or services that you want to make available on your computer (for example, Remote Desktop, a web server, and so on).
Connection to a Workplace Using DirectAccess—Select this option if you can’t access your corporate network over the Internet via the DirectAccess virtual private networking feature.
Note
The troubleshooters aren’t good at determining that nothing is actually wrong with their particular area of concern. If a troubleshooter says that it can’t find a problem, it might mean that there is no problem with that specific topic. Try another troubleshooter.
Windows displays a box that says “Identifying the problem...” and then displays a results window that explains what was found to be wrong, what Windows did about it (if anything), what the outcome was, and where to go for more assistance.
If the diagnostics tool doesn’t solve your network problem, check Windows Firewall to be sure it isn’t blocking a desired network service.
Windows Firewall
Another configuration setting that could prevent file and printer sharing from working correctly is Windows Firewall. To ensure that file and printer sharing isn’t blocked, open the Windows Firewall window. The quickest way is to type firewall into the taskbar’s search box, and then select Windows Firewall from the search results. (Or, at the Command Prompt, type wf.)
Windows Firewall filters network activity based on the type of network to which you’re attached. For both private and public networks, unless you’re using a third-party firewall product, the Windows Firewall State should be On, and Incoming Connections should be set to Block All Connections to Apps That Are Not on the List of Allowed Apps.
On the top left of the screen, click Allow an App or Feature Through Windows Firewall to view the settings. File and Printer Sharing should be checked in the Private column, but not in the Public column. Core Networking should be checked in both columns. If any of these is wrong, click Change Settings, make the correction, and then click OK.
For more information about configuring the firewall, see “Configuring Windows Firewall,” p. 405.
If the firewall settings appear to be correct, the next step is to check Windows Event Viewer, to see whether Windows has left a record of any network problems there.
Event Viewer
Event Viewer is another important diagnostic tool and one of the first to check because Windows often silently records useful information about problems with hardware and software in an Event Log. To check, open the Event Viewer, using one of these two methods:
Press Windows Logo+X or right-click the Start button, and then select Event Viewer.
In the taskbar’s search box type event, and then click View Event Logs.
Start by selecting Custom Views, Administrative Events in the left Navigation pane. It can take awhile for anything to appear. The list shows significant management events from all of the various Windows events logs (and there are a lot of them!). Look for anything that might mention a networking error.
If nothing useful appears there, select Windows Logs and then examine the System, Application, and Security logs in turn. Finally, open Applications and Services Logs, Microsoft, Windows, and under any of the network-related categories, view the Operational and Admin logs.
Event Viewer displays Event Log entries, most recent first, on the right (see Figure 22.3).
Figure 22.3 Event Viewer might display important diagnostic information when you have network problems.
Log entries for serious errors are displayed with an exclamation mark (!) in a red circle; warnings appear with an exclamation mark in a yellow triangle. Informational entries (marked with a blue i) usually don’t relate to problems. Double-click any error or warning entries in the log to view the detailed description and any associated data recorded with the entry. The Warning entry in Figure 22.3 indicates that my computer couldn’t acquire a network address in a reasonable amount of time. It turns out that my router had come unplugged.
These messages are usually significant and informative to help diagnose network problems; they might indicate that a network card is malfunctioning, that a domain controller for authentication or a DHCP server for configuration can’t be found, and so on. The Source column in the Event Log indicates which Windows component or service recorded the event. These names are usually fairly cryptic. Table 22.3 lists a few of the more common nonobvious ones.
Tip
A problem with one network system usually causes other problems. Therefore, the oldest error message in a closely timed sequence of errors is usually the most significant, with subsequent errors just a result of the first failure. Because the Event Log is ordered “most-recent first,” you might get the most useful information down a bit from the top of the list.
If you’re at a loss to solve the problem, even with the information given, check the configuration of the indicated component, or remove and reinstall it to see whether you can clear up the problem.
Device Manager
Hardware problems with your network card will most likely be recorded in the Event Log. If you suspect that your network card is the culprit, and nothing is recorded in the Event Log, check the Device Manager.
You have two easy ways to open the Device Manager:
Press Windows Logo+X and select Device Manager.
In the taskbar’s search box, type manager, and then select Device Manager from the search results.
Tip
The real cause of your problem might reveal itself at system startup time rather than when you observe the problem. Reboot your system and note the time. Then reproduce the problem. Check the Event Log for messages starting at the reboot time.
Any unrecognized devices or devices with detectable hardware problems or configuration conflicts appear with a yellow ! icon when you display the Device Manager. If no yellow icons appear, you don’t have a detected hardware problem. This doesn’t mean that you don’t have a problem, but the odds are slim that your network card is the problem.
If devices are shown with ! icons, double-click the device name to see the Windows explanation of the device status and any problems. A device that you’ve told Windows not to use (disabled) will have a circle with a downward-pointing arrow in it; this is generally not a problem.
For more detailed instructions and tips on device troubleshooting, see Chapter 26, “Troubleshooting and Repairing Problems.”
Testing Network Cables
If your computer can’t communicate with any other computer on your LAN, and the Device Manager doesn’t indicate a faulty network card, you might have a wiring problem. Wiring problems can be the most difficult to solve because it’s difficult to prove that data is leaving one computer but not arriving at another. The ping program, discussed later in this chapter, can help with this problem.
To learn how you can use the ping command to diagnose Internet-related problems, as opposed to LAN problems, see “ping,” p. 362.
If your computer is not properly wired into the LAN or is connected through a wireless network, in many cases Windows will display an offline icon right on the notification area and indicate that your network card is disconnected. It might not, though, so you shouldn’t take a lack of this kind of message to mean that no wiring problems exist.
If your network uses CAT-5 or CAT-6 cabling plugged into a hub, there’s usually a green LED indicator on each network card and at each port on the hub. Be sure that the lights are on at each end of your network cable and those for the other computers on your LAN.
You also can use inexpensive (about $50) cable-test devices that check for continuity and correct pin-to-pin wiring order for UTP wiring. They come as a set of two boxes. One gets plugged into each end of a given cable run, and a set of blinking lights tells you whether all four wire pairs are connected and in the correct order. It’s nice to have one of these devices if you install your own network cabling and/or make your own patch cables.
Checking Network Configuration
If hardware isn’t at fault, you might have a fundamental network configuration problem. Often the Event Log and Device Manager give these problems away, but if they don’t, you can use another batch of tools to check the computer’s network configuration.
ipconfig
If your computer can’t communicate with others on your LAN, after you check the Event Log and Device Manager, use the ipconfig command-line utility to see whether your computer has a valid IP address. Check other computers on the LAN, too, to ensure that they do as well.
To use this tool, open a Command Prompt window: Right-click or touch and hold the Start button and select Command Prompt or Windows PowerShell (whichever appears). Then type the following command:
ipconfig /all
Next, press Enter. The results should look something like this:
Windows IP Configuration
Host Name . . . . . . . . . . . . : java
Primary Dns Suffix . . . . . . . : mycompany.com
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : Yes
WINS Proxy Enabled. . . . . . . . : No
Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Intel 21140-Based PCI Fast Ethernet Adapter
Physical Address. . . . . . . . . : 00-03-FF-DD-CA-5F
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : fe80::ed10:dff9:693c:803d%8(Preferred)
IPv4 Address. . . . . . . . . . . : 192.168.15.108(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Lease Obtained. . . . . . . . . . : Thursday, August 6, 2015 3:13:14 PM
Lease Expires . . . . . . . . . . : Friday, August 7, 2015 3:13:26 PM
Default Gateway . . . . . . . . . : 192.168.15.1
DHCP Server . . . . . . . . . . . : 192.168.15.1
DHCPv6 IAID . . . . . . . . . . . : 201327615
DNS Servers . . . . . . . . . . . : 192.168.15.1
NetBIOS over Tcpip. . . . . . . . : Enabled
(Unless you’re troubleshooting IPv6 Teredo connections, ignore the parts that mention Tunnel Adapters.)
The most important items to look for are the following:
Host Name—This should be set to the desired name for each computer. If you can correspond with some computers but not others, be sure that the ones that don’t work are turned on and correctly named. Make sure you don’t have two computers with the same name, and that none of the computer names are the same as the workgroup name.
IP Address—This should be set appropriately for your network. If your LAN uses Internet Connection Sharing (ICS), the address will be a number in the range 192.168.0.1 through 192.168.0.254. If your LAN has a connection-sharing router, the IP address will usually use numbers starting with 192.168.x, where x is a number between 0 to 100.
If your IP address starts with the numbers 169.254, your computer is set for automatic configuration but no DHCP server was found, so Windows has chosen an IP address by itself. This is fine if your LAN uses this automatic configuration system; perhaps you’ve just connected a few computers so you can share files and printers. However, if you expected to get Internet access through your network—that is, if you use ICS or a hardware Internet connection router, or you have a more complex network with a DHCP server—this is a serious problem. Restart the connecting-sharing computer or the router and then restart your computer and try again.
Note
To learn more about IP addressing, network masks, and configuration, visit http://support.microsoft.com and search for article number 164015, “Understanding TCP/IP Addressing and Subnetting Basics.”
Network Mask—This is usually 255.255.255.0, but other settings are possible. All computers on the same LAN should have the same network mask.
Each computer on the same LAN should have a similar valid IP address and the same network mask. If they don’t, check your network configuration. You also can use the built-in Windows Repair function to help fix problems with DHCP-based (automatic) IP address assignment.
System
You can check a computer’s identification and workgroup or domain membership setup from the System window. Perform one of the following actions to open this window:
Press Windows Logo+X and select System.
Click the File Explorer icon in the taskbar. Click This PC in the left Navigation pane, and then click System Properties in the ribbon bar at the top.
Open the Start menu, and in the Search box, type system. Then select System from the search results.
Look at the bottom of the screen for the computer name and domain or workgroup name, as shown in Figure 22.4.
Figure 22.4 Your computer’s name and workgroup or domain membership are displayed at the bottom of the System window.
On a home/small office Workgroup network, the workgroup name should be the same on all computers on your workgroup LAN. All of the computer names must be different from each other.
On a corporate Windows domain network, you should see your computer’s name displayed as part of a Windows domain name (for example, my computer named bribox might be called bribox.mycompany.com on a domain network) and the domain name displayed separately. Your domain name might not include .com. It might say .local instead or use a different ending. In any case, be sure that your computer is actually a domain member. If the word Workgroup appears instead, your computer is not a domain member and will not be able to use domain logins or some domain resources.
Note
None of your computers can use the workgroup or domain name as its computer name. For example, if your workgroup is MSHOME, you can’t also name a computer MSHOME. If you find this issue on one of your computers, change that computer’s name.
Network Connections
You can manually check all installed network protocols and services and their configuration by viewing Network Connections and viewing the properties for Local Area Connection. To view this screen, open the Network and Sharing Center as discussed at the start of this chapter and click Change Adapter Settings. Right-click your Ethernet icon (or the appropriate wireless connection icon) and select Properties.
Confirm that each required protocol is installed and correctly configured. In general, the settings on each computer on your LAN should match, except that the IP address differs (usually only in the last of its four dot-separated numbers). If your LAN uses automatic IP address configuration, use the ipconfig command, described earlier, to check the settings.
Testing Network Connectivity with ping
ping is the fundamental tool for testing TCP/IP network connectivity. Because most networks today use the Internet (TCP/IP) protocol for file and printer sharing services, as well as for Internet access, most Windows users can use the ping test to confirm that their network cabling, hardware, and the TCP/IP protocol are all functioning correctly. ping sends several data packets to a specified computer and waits for the other computer to send the packets back. By default, it sends four packets and prints the results of the four tests.
To see whether the network can carry data between a pair of computers, use the ipconfig command (described previously) to find the IP address of the two computers. Then, on one computer, in the open Command Prompt window, type the following command:
ping 127.0.0.1
This command tests the networking software of the computer by sending packets to the special internal IP address 127.0.0.1. This test has the computer send data to itself. It should print the following:
Reply from 127.0.0.1: bytes=32 time<10ms TTL=128
Reply from 127.0.0.1: bytes=32 time<10ms TTL=128
Reply from 127.0.0.1: bytes=32 time<10ms TTL=128
Reply from 127.0.0.1: bytes=32 time<10ms TTL=128
If it doesn’t, the TCP/IP protocol itself is incorrectly installed or configured. In that case, check the computer’s IP address configuration or, if that seems correct, remove and reinstall the Internet Protocol from the Ethernet connection icon in Network Connections. (I have to say, in more than 20 years of working with PC networks, I’ve never seen this test fail.)
If your computer can send data to itself, go to a second computer on your LAN. Find its IP address by running ipconfig on that computer. Go back to the first computer and type the ping command again, using the address of the second computer, as in this example:
ping 192.168.0.23
Of course, you should use the other computer’s real IP address in place of 192.168.0.23. You should get four replies, as before:
Reply from 192.168.0.23: bytes=32 time<10ms TTL=32
Reply from 192.168.0.23: bytes=32 time<10ms TTL=32
Reply from 192.168.0.23: bytes=32 time<10ms TTL=32
Reply from 192.168.0.23: bytes=32 time<10ms TTL=32
These replies indicate that you have successfully sent data to the other machine and received it back.
If, on the other hand, the ping command returns Request timed out, the packets either didn’t make it to the other computer or were not returned. In either case, you have a problem with your cabling, network adapter, or the TCP/IP protocol setup. Another problem could be that Windows Firewall or a third-party firewall product is blocking the ping data. This will almost certainly happen if the computer you are pinging has its network location set to Public rather than Private.
Note
If you enter a computer name, and ping can’t determine the computer’s IP address, the problem isn’t necessarily a wiring problem. It could be that the DNS or WINS name lookup system is not working correctly. Try using an IP address with ping in this case to help determine what the problem really is.
You can use ping to determine which computers can send to which other computers on your LAN or across wide area networks (WANs) or the Internet. ping should also work when given a computer’s IP address or its network name.
Diagnosing File and Printer Sharing Problems
If the test in the previous section doesn’t point to a problem—that is, if basic network connectivity is fine but you’re still having problems with file or printer sharing—the next step depends on whether you have a workgroup or domain-type network.
If you’re on a domain network, it’s time to call your network administrator for assistance. He or she has more training and experience in network troubleshooting than we can impart in the space allowed here.
If you’re on a home or small office workgroup network, there are a few things you might try. Here are some tips:
Did you make sure that file sharing is enabled on each of your computers?
Do your Windows 10, 8.1, or 8 computers say Private as their network location? Do your Windows 7 and Vista computers say Home or Work? The Public setting blocks file sharing.
On Windows XP, there is no network location setting. Instead, open Windows Firewall, view the Exceptions list, and make sure that File and Printer Sharing is checked.
If you use Internet Connection Sharing, restart the computer that’s sharing your Internet connection and wait a minute or two after it’s booted up. Then restart your other computers. This may help. The ICS computer needs to be up and running before any other computers on your LAN start up. Similarly, if you use a connection-sharing router, wired or wireless, unplug it, wait a few seconds, and then plug it back in. Wait about a minute and see if this has fixed the problem.
If you can see the folders shared by another computer but can’t move any files into them, or edit files in them, then your network is fine. You just have a permissions problem. On the computer that is sharing the folders, be sure that the folders are shared so that remote visitors can change files.
For more information on shared folders, see “Using Shared Folders in Windows 10,” p. 454.
If the sharing computer has Password Protected Sharing enabled (or has Simple File Sharing turned off, if the computer is running XP), the owner of that computer should check to see that your user account has permission to read and/or modify the files in the shared folder. In the folder or files’ Security properties, check to see that your user account is listed or that the group you’re in (for example, Users or Everyone) has the necessary permissions.
For more information on file permissions, see “Setting Security Permissions on Files and Folders,” p. 754.
In Windows 10, 8.1, 8, and 7, Password Protected Sharing works differently than it does on Vista and XP. If you can’t access a file over the network that you know you could access if you were signed in directly at the sharing computer, that computer might be using the Guest account to access the file instead of yours.
For more information on Password Protected Sharing, see “Configuring Passwords and File Sharing,” p. 784.
One way you can tell whether this feature is causing your problem is to sign in at the sharing computer. Next, in File Explorer, right-click This PC, or in Windows Explorer, click [My] Computer, and then select Manage. In the left Navigation pane, open the Shared Folders item and select Sessions. Try to access the problem file or folder from across the network. You should see an entry for the networked computer. If the username is Guest, you will only be able to read or write files that group Everyone can read or write. See Chapter 33 for a discussion about the way Password Protected Sharing works in various situations.