How to Fix Sndvol32.exe Error

Lately, Microsoft has trying to fix Print Nightmare with various methods and patches. The last patch has seemingly fixed Print Nightmare but it has broken the Alt-tab key combination. It has been reported that the latest patch has broken famous key combinations for quickly switching from window to window. It seems that combination is not working or it is switching to desktop, even going to blank screen if switching from the full-screen game.

Fixing the issue

Luckily this issue is easily fixable. The first and easier fix for this issue is surprising to turn off the news and info widget, right-click on it and choose News and interests and then click on turn off. The second solution would be to uninstall the update. Go to Settings, then to Update & Security, and from there view Update History and remove the update.

Installing Windows updates, installing a new driver from the manufacturer, or even just installing an application or game can cause sometimes certain components of your computer to stop working properly or introduce issues that were not present just before mentioned installation. Luckily for all of us, Microsoft seems aware of this potential issue and we have the option to roll back an older driver which performed well and had no issues at all. In order to do this first press ⊞ WINDOWS + X to open the hidden start menu and click on Device Manager. From the Device Manager choose the troublesome device and right-click on it, choose properties. Device properties floating Window will appear. Click on the top tab which says, Driver. From the Driver tab, click on Roll Back Driver. Note that if the device is working properly, the Roll Back Driver button will be greyed out and you will not be able to click on it meaning that chosen device is not the issue. If the device is not working properly and you can click on Roll Back driver, do it, choose the previous version, and reboot your computer. You can use this method to get back to the previous driver version for any device that is causing issues in your computer.

You can prevent starting of app installations files if they have not come from the MS store inside Windows 11. This can make your PC more secure because all apps in the store will have to be digitally signed and overall it can provide you with more control over what will be installed. Follow the guide below to find out how can you easily turn this feature ON.

1. Press ⊞ WINDOWS + I to open Windows settings
2. Select Apps and then choose Apps & Features
3. Click on Choose where to get apps to bring a drop-down menu
4. Select The Microsoft Store only (Recommended)
5. Close settings

Settings will apply changes immediately and you continue using Windows right away. With these settings turned ON if you want to install a downloaded application or run the installer you will not be able to, and message The app you’re trying to install isn’t a Microsoft-verified app will show on your screen. You can always reverse this setting by choosing Anywhere in settings instead of Microsoft store only.

This post will guide you in fixing high CPU, Memory, and Disk usage problems caused by NTOSKRNL.exe. NTOSKRNL stands for “NT Operating System Kernel. This file is a kernel image that is responsible for a lot of systems-based processes such as Hardware Virtualization, Process, and Memory. Aside from that, it is also the one that compresses the old pages of memory that reduces the overall amount of memory being used. If you notice that your computer is running slowly and you find that the NTOSKRNL.exe file is hogging your resources such as disk usage, CPU usage as well as memory usage, then read on as this post will guide you in fixing the problem caused by NTOSKRNL.exe. Make use of the options given below to resolve the issues caused by NTOSKRNL.exe. 1] Scan your computer for potential malware There might be a good chance that your computer might be infected with malware. And this malware might be associated with the NTOSKRNL.exe file and hence making it consume a lot of system resources. So, I would really recommend you to make sure that your Antivirus is up to date and then scan your computer with it specifically the C:/Windows/System32 folder because this is the location where the NTOSKRNL.exe file is located.

Option 1 – Put your computer in a Clean Boot State

The first thing you have to do is to put your computer in a Clean Boot State as this can help you in finding any incompatible programs that are causing the problem.

• Log onto your PC as an administrator.
• Type in MSConfig in the Start Search to open the System Configuration utility.
• From there, go to the General tab and click “Selective startup”.
• Clear the “Load Startup items” check box and make sure that the “Load System Services” and “Use Original boot configuration” options are checked.
• Next, click the Services tab and select the “Hide All Microsoft Services” check box.
• Click Disable all.
• Click on Apply/OK and restart your PC. (This will put your PC into a Clean Boot State. And configure Windows to use the usual startup, just simply undo the changes.)
• From there, start to isolate the problem by checking which one of the programs you installed recently is the root cause of the problem.

Once you’ve found any incompatible programs, you need to uninstall them. Refer to the steps below to do so.

• In the search box, type in “control” and then click on Control Panel (desktop app) among the search results.
• After that, select Programs and Features from the list which will give you a list of all the programs installed on your computer.
• From there, look for the concerned program and select it and then uninstall it.

Note: If you have downloaded the app from the Windows Store, you can simply right-click on it from the application list and then uninstall it.

Option 2 – Update or rollback drivers

If the first option didn’t work for you, then it’s time to either update or roll back the device drivers. It is most likely that after you updated your Windows computer that your driver also needs a refresh. On the other hand, if you have just updated your device drivers then you need to roll back the drivers to their previous versions. Whichever applies to you, refer to the steps below.

• Open the Devices Manager from the Win X Menu.
• Then locate the device drivers and right-click on them to open the Properties.
• After that, switch to the Driver tab and click on the Uninstall Device button.
• Follow the screen option to completely uninstall it.
• Finally, restart your computer. It will just reinstall the device drivers automatically.

Note: You can install a dedicated driver on your computer in case you have it or you could also look for it directly from the website of the manufacturer.

Option 3 – Try to run the DISM tool

If the first two options didn’t work, then running the Deployment Imaging and Servicing Management might. Using this built-in tool, you have various options such as the “/ScanHealth”, “/CheckHealth”, and “/RestoreHealth”.

• Open the Command Prompt with admin privileges.
• Then type in the following commands and make sure to hit Enter right after you type each one of them:
  • Dism /Online /Cleanup-Image /CheckHealth
  • Dism /Online /Cleanup-Image /ScanHealth
  • exe /Online /Cleanup-image /Restorehealth
• Do not close the window if the process takes a while as it will probably take a few minutes to finish.

Option 4 – Try to stop the Runtime Broker process

The RuntimeBroker.exe or the Runtime Broker process is the one that monitors access to Windows APIs to make sure that the apps do not violate the core security of Windows. This process usually leaves a very small footprint. However, there are times when it consumes more resources than it’s supposed to and does not release memory after the work is done that results in a memory leak. As a result, it affects NTOSKRNL.exe which is why you have to stop the Runtime Broker process. To do so, refer to these steps:

• Tap the Ctrl + Shift + Esc to open the Task Manager.
• After opening Task Manager, go to the Processes tab and look for the Runtime Broker process.
• Once you find it, check if it is using more than 15% of your memory. If it is, then you most likely have an issue with an app installed on your computer.
• Select the Runtime Broker process and right-click on it and then click on the End Task option to end its process.

Option 5 – Try to run the Performance Troubleshooter

• Tap the Win + R keys to open the Run dialog box.
• Type “msdt.exe /id PerformanceDiagnostic” in the field and hit Enter to open the Performance troubleshooter.
• Then click on Next to get started. Wait until the process is completed.

Option 6 – Try using the Windows Performance Toolkit

You can also use the Windows Performance Toolkit in finding the root cause of the problem. Just refer to the following steps to use this toolkit.

• Search for “cmd” in the Cortana Search box and click on Command Prompt from the search results to open it.
• Next, type in the command given below or copy and paste it and then hit Enter:

xperf -on latency -stackwalk profile -buffersize 1024 -MaxFile 256 -FileMode Circular && timeout -1 && xperf -d cpuusage.etl

• After executing the command, wait for at least 60 seconds and then check the logs of the Windows Performance toolkit which is stored in a file named cpuusage.etl in the folder located at C:/Windows/System32. From there, you should see a list of all the causes of the System Resources being hogged.

In today's digital life, when we access the internet daily, browsers are essential almost as our operating system, after all, we do access all of the internet data via them, and having a good, reliable, and personal browser tailored for our needs can make all the difference in the world. In today's article, we will introduce you to the five greatest browsers of today, we will point their advantages and disadvantages and why should you pick one or another. As with each piece of software, there is not an ultimate browser, better than anything else and we will not favor anyone on this list, the decision which you should use is solely up to you, we are here to provide you with an objective opinion on each one. All of this being said, let's begin with the countdown in no particular order.

1. Mozilla firefox.

   If you consider yourself a power user or you value your privacy then firefox is the browser for you. It is open source and is packed with great features like reporting when your email has been used for a known data breach, it stops annoying pop-up notifications, stops browser fingerprinting, and many more. Firefox is also a cross-platform browser making it a great choice if you want to transfer and use your data across multiple devices with one account. The downside of firefox however is its speed, this browser is the slowest on this list, I guess features and advantages took their tool in the speed department, but if that is not a concern for you and you feel like the positives outweigh some slower speed, grab it here.

2. Google Chrome

   Chrome browser has been a game-changer when it was released and even today some of its features are still great and needed. It is packed with some great features like tab freezing, for example, it is cross-platform meaning that also as firefox you can change data between browsers on different devices. it is a very expandable browser with tons of extensions and its speed performance is very very good. The downside of Chrome are two things sadly, one of them is its hunger for RAM, the browser takes a big chunk of RAM once it is active and on some older computer with limited RAM it performs slowly, another is telemetry which its sending, in other words, other browsers don’t come with the lingering fear that Google’s just a little bit too involved in all of our lives. But if downsides do not trouble you and you have a decent amount of RAM in your system chrome might be the best solution for you, grab it here and check it out.

3. Microsoft Edge

   Or should I say Microsoft edge 2.0 since this new Edge is completely recoded and rethought, a completely new browser based on chromium. The first version of the edge was an inhouse attempt from Microsoft and it was a disaster, I guess the lesson was learned, and this new edge we have today is a great Browser, it is lightning fast and packed with some great features with one among them standing out I just love, that is the ability to save web pages as applications and truth to be told you have to try this in order to see al great advantages it offers. A very interesting feature is that edge itself wins the speed race from all of the 5 contestants here which is a great surprise. Of course, the downside of annoying Microsoft pushing it to be your default is, well it's Microsoft, as chrome is tied to Google so is edge tied to Microsoft, and the same dreaded feeling that big MS is watching you. If however, you do not concern yourself with these kinds of things, since it is already part of Windows 10, give it a spin and try it, I am sure you will at least love its blazing speed.

4. Vivaldi

   A new kid on the block, relatively unknown Browser Vivaldi offers some great customizable features no other one on this list offers, a very unique and down to each detail customization option, you can literally tweak each and every aspect of this browser making it best customizable and personal browser ever. How it is also based o chromium, every chrome extension works in it naturally. It is very good in speed and constantly updated and developed. The downside, well if you are anything like me, you could spend ages trying to customize it, ages, it has tons of features, and making it really feel and tick as you want can consume a really lot of time. If this thing does not bother you at all, grab Vivaldi here.

5. Opera

   Last but not least, we have another relic of the old browser age, the Opera browser. Packed with great security and great in-house features like a built-in VPN, built-in ad blocker, built-in crypto wallet, etc this browser seems like a swiss army knife. Opera is full of features and it shows once you start using it. The downside of opera is that its look and feel are specifically tailored to a certain type of user and not everyone will find that appealing or attractive, add some great but hidden and hard to come by features and it may go unnoticed. However, I think you should really give it a go since it definitely deserves more attention than it gets. Grab it here and check it out.

That's it, 5 great browsers to look up, I hope that you have enjoyed the read and I hope to see you again here for more articles. If you would like to read more helpful articles and tips about various software and hardware visit errortools.com daily.

In case you don’t know, Windows 10 now allows users to check the Bluetooth battery level of devices. More often than not, the accessories or peripherals users use for their Windows 10 devices are connected to it using Bluetooth technology. This high-speed low-powered wireless technology is designed to link mobile devices, computers, and other network devices over a short distance wirelessly. Monitoring the battery level of a device where Bluetooth is enabled isn’t an easy task as most of these devices do not support the Bluetooth battery monitor or the battery level display. And even when on devices that do, you still have to install additional software to find it. However, Windows 10 eliminates this requirement and all you have to do is add a Bluetooth device and connect that Bluetooth device. How? Follow the instructions provided below. Step 1: Adding a Bluetooth Device The easiest way to get your Bluetooth device battery to be displayed on your Windows 10 screen is to simply add a Bluetooth device. To do so, follow these sub-steps:

• First, turn on the Bluetooth mode on your device.
• Next, go to Windows Settings > Devices > Bluetooth & other devices.
• From there, click on the “+” button next to the ‘Add Bluetooth or other devices” option and select the type of device you want to add.

Step 2: Connecting the Bluetooth Device Once you’ve added the device, it will be visible under the “Add a device” screen.

• Now select the newly added Bluetooth device and click the “Done” button.
• After that, it will now be connected. Go back to the “Bluetooth & other devices” window and scroll down to the section of “Mouse, Keyboard, and Pen”.
• From there, move the cursor alongside the connected device to display its battery level.

Keep in mind that there are several ways in which you can display the battery information of the Bluetooth device. However, Windows 10 understands only one of them per se. So if your device is not a Bluetooth Low Energy device, Windows 10 won’t be able to show its battery information and won’t display its battery level.

Living in today's world sadly is still living in the COVID-19 pandemic. It has been more than a year and sadly pandemic is still very strong and we are battling it on a daily basis. Governments all over the world are trying to battle pandemics in their own way with their own ideas and prevention measures. We as individuals can not very much influence how will the pandemic itself go but fortunately in this modern age of information we can at least follow and be in the loop at the current state of the situation regarding it. Today instead of having a troubleshooting article or tips and trick for your PC we are doing something else but in the domain of internet technology, you know, just to keep everything still IT related ???? Below you will find websites with small descriptions of what they do to keep yourself informed and hope to get over this dreadful pandemic.

1. The WHO’s COVID-19 Dashboard

   If you are interested in real-time COVID-19 information about active cases, death tool so far, new cases and the number of vaccines administrated so far I would recommend WHO's dashboard. How WHO is a non-government institution composed of doctors from all over the world with just a single goal in mind, to help and put an end to this pandemic is a great non-biased source of information on the current state of virus spread.

2. Vaccine Finder

   Please be aware that Vaccinefinder is working only on the territory of the United States of America. The reason why it was included in this list is that basically it is a great idea and I hope to see this site expand on other world regions or at least that inspires the emergence of another worldwide website with this type of content. If you live in the USA, this site will be a great help since you can track where and how many shots are distributed to states and even towns in America.

3. COVID tracking project

   This site is also for U.S. residents, this time it is about tracking cases in each state with details and statistics. If you are interested in more detailed statistics of hospitalized patients per state or overall you are just interested in statistics about the pandemic in the U.S. this site might provide all the information about your needs.

4. NPR

   On national public radio or NPR for short, there is a special section devoted to the coronavirus where new articles about pandemic are released daily with new information and new findings on how to battle it and the current state of things. A great informational site to keep up with the current state of things.

5. Google's COVID-19 page

   Google has not been inactive during this pandemic and on its page specially dedicated to the COVID-19 virus you can find a lot of free information updated daily. From safety and prevention tips to data about pandemics there is a lot of ground covered on-page and we recommend at least going through the prevention section to inform yourself how to keep yourself and others safe.

6. Coronavirus tracker

   This daily updated chart can show how many cases and deaths are from chosen time period all in form of a chart, you can see charts for each country in the world how COVID cases rose or dropped along with the death tool it brought.

There you go, 6 websites to track and inform yourself about this dreaded pandemic which has managed to change the world and people's lives forever, sadly on the bad side.

The number of Hertz is the number of how many images your screen draws in one second. So monitor with a refresh rate of 60Hz will draw 60 images each second on your screen. To most users, this will look fine and enough but actually, if you would place them in front of a 120Hz screen difference will be visible right away.

Benefits of higher refresh rates

In most simple words just looking at a screen that has a higher refresh rate will produce a more natural feel of things, although some people would argue that flickering can not be seen on 60Hz monitors and that should be enough, I would argue that they never watched the movie, played the game or used high refresh rate screen when they can state something like that.

Yes, 60Hz might be enough to look at the web page or read some documents but long exposure to 60Hz can have a tiring effect on the eyes in the long run. 120Hz and above just feel more relaxed and it is far less demanding on the eyes. Watching movies also is much better on a higher refresh screen, with way much less motion blur in fast scenes giving the overall experience a greater natural feel.

Gaming is perhaps an area where a refresh rate of 120Hz and above will show its best. Having a higher refresh rate will be easier on your eyes and can even give you a competitive edge. When for example you have twice more images per second on your screen than your opponent his movement will be more fluid and predictable because of that and overall precision will be much higher when moving the cursor in the game since more frames per second means more precision and smoother movement.

The dark side of high refresh rates

After all the positive things that were said about the advantages of high refresh rates, it is just fair to look at some negatives or in this case only negative one and that is Computer power. As said in the previous section having a 120Hz refresh rate means having 120 frames displayed on the screen per single second. Having even higher monitors like 360Hz means even more frames per second and in order to actually see all of that frames you will need to have enough computer power to back it up. Having for example screen with a refresh rate of 240Hz means nothing if your GPU and rest of the computer are able only to push 150 frames per second, in this case, you will still have 150 frames in one second despite the monitor being able to go to 240.

Conclusion

Generally and with all of my heart I would recommend moving away from 60Hz monitors, yes they are cheaper and more affordable but at the end of the day if you are someone like me who spends most of his daily time in front of the computer you would be grateful to have higher refresh rate screen and save your eyes, and after all, why not enjoy some smoother and better movie and game experience as well as saving your eyesight.

nslookup is a command-line tool that helps in finding the DNS records of a website. It sends a name server query to the DNS and obtains the corresponding IP address. Aside from that, it can also perform some complex functionality such as finding details about FTP server, Mail server and many more but most of them are used by administrators. The best thing about nslookup is that it queries the DNS server directly and it does not rely on the cache. On the other hand, there is another tool called PING that is used to verify connectivity. PING sends a packet of information to the IP address or Domain and gets back a response in the form of packets. So if everything goes well, all packets are received but if not, it will help you find out where the delay in the network exactly is. However, the ping command does not always attempt a DNS lookup which means that it might be using the DNS cache and use the IP address available in that table. Although both nslookup and PING help you in identifying the host or IP address, however, they don’t always work and sometimes fail. So if your nslookup works but ping fails on your Windows 10 PC when querying the IP address of a website then it could be caused by many reasons. It could be that the nslookup queries work for you but when you try to use PING, it fails. For instance, if you open the abc.com website, here’s how it will look like:

nslookup xyz.com Server: dns.company.com Address: 192.168.1.38 C:> ping xyz.com Ping request could not find host xyz.com. Please check the name and try again.

The domain is converted into an IP address and then data is sent to that IP address when you use PING. So when a reply comes back it means that the data is going back and forth to that domain without any problem. However, if the DNS fails to resolve the IP address of the website or if your PC does not attempt a DNS lookup, you will receive a similar error message that says, “Could not find host” and so on. To resolve this issue, here are some options that might help.

Option 1 – Reset Winsock, TCP/IP & Flush DNS

Resetting Winsock, TCP/IP, and flushing DNS might help you resolve the issue with nslookup and PING. To do so, follow these steps:

• Right-click on the Start button and click on Command Prompt (administrator) so you can pull up an elevated Command Prompt.
• After that, execute each one of the commands listed below. And after you typed in one after the other, you have to hit Enter.

1. netsh winsock reset – type in this command to reset Winsock
2. netsh int ip reset resettcpip.txt – type in this command to reset TCP/IP
3. ipconfig /flushdns – type in this command to flush the DNS cache

• Next, restart your PC and check if the problem’s fixed.

Option 2 – Force Windows to do a DNS lookup using FQDN

• Go to Settings > Network & Internet > Status > Change adapter options.
• From there, right-click on the network and select Properties.
• Next, in case you’re using IPv6, from the list of connections available in the list, select Internet Protocol Version 4.
• Then click on Properties and click Advanced.
• After that, switch to the DNS tab and select “Append these DNS suffixes (in order)” and click on the Add button and then add “.” as a suffix so that each time you query using PING and another tool, it will add a “.” at the end and will force the lookup.

Option 3 – Make sure that there is only one default gateway

If your computer has more than one NIC connected and there are multiple default gateways, then it will most likely create confusion which is why you need to remove the default gateway from the configuration of all NICs and make sure that there is only one default gateway.

Option 4 – Use the Google Public DNS

You might want to change your DNS to Google Public DNS as it could also help you in fixing the nslookup and PING issues. To do so, follow the steps below.

• The first thing you have to do is right-click on the network icon in the Taskbar and select Network and Sharing Center.
• Next, click on the “Change Adapter Settings” option.
• After that, search for the network connection that you are using to connect to the internet. Note that the option might be “Wireless Connection” or “Local Area Connection”.
• Right-click on your network connection and click on Properties.
• Then select the new window to choose the “Internet Protocol 4 (TCP/IPv4)” option.
• After that, click on the Properties button and click the checkbox in the new window for the option “Use the following DNS server addresses”.
• Type in “8.8.8.8” and “8.8.4.4” and click OK and exit.

Option 5 – Check the Windows Host file

You can also try to cross-check the Windows Hosts file to find out if the website you are trying to open has been blocked, because if it is, then it’s no wonder why PING fails even when nslookup works. There are instances when some third-party application modifies the file and adds some websites to the blocklists. So if the website is indeed blocked, you need to remove it from the list.

Option 6 – Delete the WLAN Profiles

Deleting the WLAN Profiles might be a good idea if you are not able to connect to the internet on your computer and if you’re using Wi-Fi. It could be that the networks that were connected previously have gone rogue which is why it is not connecting properly. And so deleting the WLAN profiles might help you in fixing the issue with nslookup and PING.

Option 7 – Reinstall the Network Adapter Drivers

• Tap the Win + R keys to launch the Run window and then type in the “msc” command and hit Enter to open the Device Manager window.
• Under the Device Manager, you will see a list of drivers. From there, look for the Network Adapters and expand it.
• Then right-click on each one of the Network drivers and select “Uninstall device”.
• Restart your PC.

The fltmgr.sys file or the Filter Manager is the one that’s responsible in making sure that all the file stored in a computer’s hard drive stays on their respective locations and is located in C:/Windows/System32/drivers. Now when you encounter a Blue Screen of Death or BSOD error saying, “Your PC ran into a problem that it couldn’t handle, and now it needs to restart. SYSTEM_SERVICE_EXCEPTION”. This kind of Stop error is due to an error with the driver that’s responsible for enabling the communication between the hardware and the computer. It indicates that this driver allows direct access to the internal hardware from the CPU itself. What’s worse about the SYSTEM_SERVICE_EXCEPTION BSOD error is that there are times when you won’t be able to log in to your computer even after it reboots. However, you need not worry as this post will guide you into fixing this BSOD error. All you have to do is follow the given options below carefully and that before you proceed make sure that you create a System Restore point just in case something goes wrong.

Option 1 – Run the Windows Update

Obviously, since the fltmgr.sys file is a system file from Microsoft, you can try running the Windows Update and see if it fixes the problem or not.

Option 2 – Run the System File Checker

The System File Checker, also known as the SFC scan, is a built-in utility in Windows that can be found in the C:/Windows/System32 folder. This tool allows you to scan and restore any corrupted system files in Windows that might be causing the SYSTEM_SERVICE_EXCEPTION BSOD error. To use this tool, follow the steps below.

• Tap Win + R to launch Run.
• Type in cmd in the field and tap Enter.
• After opening Command Prompt, type in sfc /scannow

The command will start a system scan which will take a few whiles before it finishes. Once it’s done, you could get the following results:

1. Windows Resource Protection did not find any integrity violations.
2. Windows Resource Protection found corrupt files and successfully repaired them.
3. Windows Resource Protection found corrupt files but was unable to fix some of them.

• Restart your computer and then check if it has fixed the error or not.

Option 3 – Run the Blue Screen Troubleshooter

The Blue Screen troubleshooter is a built-in tool in Windows 10 that can be found on the Settings Troubleshooters page. To use it, refer to these steps:

• Tap the Win + I keys to open the Settings panel.
• Then go to Update & Security > Troubleshoot.
• From there, look for the option called “Blue Screen” on your right-hand side and then click the “Run the troubleshooter” button to run the Blue Screen Troubleshooter and then follow the next on-screen options. Note that you might have to boot your PC into Safe Mode.

Option 4 – Check your hardware for any physical issues

There are times when faulty hardware can result in serious problems in the system such as the SYSTEM_SERVICE_EXCEPTION Blue Screen error. Thus, it is highly recommended that you check the internal components of your CPU to find out if there are any problems. And if there is any physical damage, you need to bring that to a technician to get it fixed or have it replaced.

Option 5 – Run the CHKDSK utility

You can also run the Chkdsk utility to resolve the BSOD error. The Chkdsk utility is the one that repairs hard drive errors that might be causing the problem.

• Open Command Prompt with admin privileges.
• After opening Command Prompt, execute the commands listed below, and don’t forget to hit Enter right after you type in each one of them and if you have installed Windows to some different directory, you must replace “C” with the name of the drive you’ve installed Windows with.
• chkdsk C: /r /x
• chkdsk C: /f