Tag Archives: common mistake

Troubleshoot a Slow Computer Network – Only One Computer on the Network is Slow

Only One Computer on the Network is Slow

Client Computer Network Mask Wrongly Configured
Your network is a class C network, (net-mask 255.255.255.0), and your client computer has its IP address configuration on a class B network, (255.255.0.0). Change the network mask of the client to match the network configuration.

Poor network cards
Bad network cards or bad drivers are very often the reason for poor transfer rates. Test the transfer rate with a different network card.
An outdated computer can also slow down your network transfer.

Bad Network Configuration
DNS Configuration
can be the cause a of slow network connections.
Wrong DNS address in the IP configuration can slow your network dramatically. Your DNS client will try to connect to an inexistent or not working DNS server then give up and try your secondary DNS server. This translates in slowdowns and sometimes even DNS resolution errors.
Fix: Ping the DNS address or, even better, use nslookup and connect to both of your DNS servers to check if they work.

The TCP/IP protocol stack corrupted.

Sometimes no matter what you do you can’t fix the network and this is because the TCP/IP becomes corrupted. The only thing that fixes it is a reset. On older Operating Systems, such as Windows 98 and Windows NT, the fix was to uninstall and reinstall the whole TCP/IP suite of protocols.
Fix: issue the following command to reset it: netsh int ip reset c:\resetlog.txt.

More Than One Default Route
Advanced Lan SettingsA very common mistake is to assign more than on default route to the same computer. Do not confuse load balancing with multiple Default Gateways. You are configuring two network cards, and both of them have a default gateway. This configuration will not work. Usually, a Windows computer will warn you that this is not a good idea, but some users will choose to ignore the warning.
This is a typical problem for laptop users, they connect into the Lan environment and leave the wireless connection on. This will create a lot of problems for corporate users and even for home users.
In order for this type of configuration to work, special routing rules and IP configuration is needed. it is easier to turn the wireless of or have an adapter manager that will automatically do that for you based on your rules.
Advanced Tcp/IP Settings
On a Windows XP there is a way to assign priorities to network cards using a graphic interface. from the Network Connections applet in the Control Panel, click on the Advanced menu and choose Advanced Settings.
On the Advanced Settings window arrange the network cards according to the correct priority.
Another way to achieve this is to change the gateway’s metric for each of the network adapters on the computer. To do this, open the TCP/IP properties on each of the network addapters with a default gateway configured, and click on the Advanced button. On the Advanced TCP/IP Settings window, uncheck the Automatic Metric for the Default Gateway, and enter a value according to your network topology. The lower the metric, the higher the preference for a default route.

This article is part of a five posts series regarding Network Troubleshooting.

How to Improve Internet speed at your Business

How to Improve Internet speed at your Business

If you are a Business owner or a System Administrator and the Internet connection is an important piece of your business, you probably know how difficult it is sometimes to keep a good balance between the real needs and the perfect Internet Connection.

Most of the times the first impulse is to make a connection upgrade and many times, this is the right step. Sometimes however we can improve a lot the Internet usage without upgrading. This article will show you what to do to improve the Internet speed without upgrading.

What is the Root Cause of your Slow Internet

Determine if the problem is the Internet Connection Bandwidth.
Many times the problem is the computer or the Local Area network. If your network was installed by your cousin or a friend who “New How to Do IT” it is likely that this is your problem. Check this article to learn “How to Troubleshoot a Slow Network.”(coming soon)
Use an Internet Connection Speed Test and determine if the connection performs at parameters.

Implement policies for the Internet use.

Very often companies don’t have a policy for Internet usage and employees abuse it and use it for personal use.
Educate employees about the day to day operations.
Many people don’t know what is acceptable to do and not to do on Internet. For Instance listening radio over Internet is a total waste if you don’t have huge bandwidth. Internet phones take a lot of bandwidth use whenever possible a regular phone. Video streaming are big bandwidth consumers. Users sometimes download files two or three times just because they don’t know where that file goes after the download. Many times they don’t even have the right to install or the file is already saved on an internal server. Sending files as attachments is another common mistake, especially if your mail server is hosted outside the company. Users will always prefer to send files via email than via a file server. A 15 Mb file will generate an Outlook message of around 18Mb. This 18 Mb will be uploaded to the email server which is the more painful operation on an asynchronous DSL connection (download is 3M but upload is 800K), and then will be again downloaded. If this email is sent to a few people imagine the connection bottleneck created.

Using a Caching Proxy could save you Money

If after all of the previous steps your business is still too slow you can implement a Caching Proxy. A Caching Proxy Server is an extremely useful tool to optimize Internet connection utilization and security. A Caching Proxy Server will cache the most used data and then serve it to its next client from the local copy rather than the Internet. A proxy will increase security in the company by providing an additional layer between the client and the Internet. It will help you enforce policies and control Internet Usage. It is also a great tool to log the Internet activity of your users. The downside of a proxy server is that is not easy to administrate, it needs an IT professional.

Caching Proxy Software

Two of the most used Caching Proxies are Squid and Microsoft ISA Server. Both of them are great tools extremely customizable and flexible. ISA Server is a rather expensive product but it has the advantage of a visual administration interface. On the other hand Squid is free software, but it needs command line administration. Another major advantage of Squid is that it doesn’t need too much hardware resources, and if configured properly can deliver excellent services.

A good companion for squid is a Content Filter. A content filter is a program that filters the access to Internet based on rules specified by the Administrator, public lists of known offensive websites and heuristic analysis. Two good content filtering programs are DansGuardian and SquidGuard.

Your Internet Usage Policies have to be Relaxed

As a closing paragraph I would recommend to keep a balance between business and personal use depending of the nature of your business. My experience showed that an extreme restriction would deteriorate the work climate and make your employee unhappy. On the other hand security and control of Internet Access are a very important factor and employees should understand this.