How often does Windows NTP correct the clock against the NTP server?
Well after many hours of investigating I found the answer is more complicated that I thought. An entire list of settings and defaults can be found here:
http://technet.microsoft.com/en-us/library/cc775797.aspx
To answer this question the important registry key is The "MaxPollInterval" registry key. This key controls in timing at which the computer will query for NTP time.
The Key can be found here:
HKLM\SYSTEM\CurrentControlSet\Services\W32Time\Config
Data type = REG_DWORD
Default value = 15
Description
Specifies the longest interval (in units of 2 to the n power seconds, where n is the value of this entry) that is allowed for system polling. While the system does not request samples less frequently than this, a provider may refuse to produce samples when requested to do so.
(http://technet.microsoft.com/en-us/library/cc739293.aspx)
The clock then corrects itself based on other values in the registry in its range. So basically if left at default it will poll every 32,768 seconds or 546.1333 Minutes or 9.10222 Hours.
The Correction
The "FrequencyCorrectRate" registry entry Controls the rate at which the time service corrects the clock.
The Key can be found here:
HKLM\SYSTEM\CurrentControlSet\Services\W32Time\Config
Data type = REG_DWORD
Default value = 4
The Effect this key has is One over the rate at which the clock is corrected. If this value is too small, the clock will be unstable and will overcorrect. If the value is too large, the clock will take a long time to synchronize.
(http://technet.microsoft.com/en-us/library/cc775797.aspx)
This value, in units equal to the reciprocal of the rate at which the clock is corrected, is multiplied by the number of clock ticks in 64 seconds, to produce the base gain in the phase-locked loop (PLL) of the clock correction algorithm.
(http://technet.microsoft.com/en-us/library/cc738293.aspx)
Ok that's nice, but what does that translate to?
Well basically there is a correction algorithm that is built in that will correct the clock in small increments until it is in sync with the source. I could not find this algorithm so if you know what it is please post it in a reply.
If you have more questions about Windows Time Service check the official blog at:
http://blogs.msdn.com/w32time/default.aspx
Internet Time Sources
If you are looking for an external time server the PDC or Primary NTP server for your facility should point externally. NIST or the National Institute of Science and Technology keep the world clock for the US which is in Boulder, Colorado. They also keep several servers around the USA running for people to sync to. You can find the list at:
http://tf.nist.gov/tf-cgi/servers.cgi
Agile Development Practices suggest developers keep a solutions log. I think we can all benefit from a combined solutions log. As I encounter errors or problems I intend to record the solutions on this blog. Please feel to leave your comments, solutions and email me with your errors and solutions.
Dec 31, 2008
Dec 29, 2008
How to Install a plug-in or update Eclipse
Obtain the update site url from the eclipse plugin you would like to add or update. This can usually be found on the project web site.
Open Eclipse > Help > Software Updates > Available Software [tab] > Add Site [button] > Add url to the location field > Check the appropriate options under the update site > Install [button]
Open Eclipse > Help > Software Updates > Available Software [tab] > Add Site [button] > Add url to the location field > Check the appropriate options under the update site > Install [button]
How to disable XML and other Validation in Eclipse
Window > Preferences > Validation and uncheck the appropriate Validator. This will also help speed up the Eclipse refresh time.
Dec 11, 2008
MD5 Password Generation via Linux
You can run the following command in Linux to generate an MD5 password:
echo -n "the_password" | md5sum
echo -n "the_password" | md5sum
Nov 18, 2008
GUI Tool for working with Web Services
soapUI is a free and open source desktop application for
It is mainly aimed at developers and testers providing or consuming Web Services (Java, .net, etc). Functional and Load Testing can be done both interactively in soapUI or within an automated build or integration process using the soapUI command line tools.
http://www.soapui.org/
- inspecting Web Services
- invoking Web Services
- developing Web Services
- Web Services Simulation and Mocking
It is mainly aimed at developers and testers providing or consuming Web Services (Java, .net, etc). Functional and Load Testing can be done both interactively in soapUI or within an automated build or integration process using the soapUI command line tools.
http://www.soapui.org/
GUI Tool Alternative to Keytool
Portecle is a user friendly GUI application for creating, managing and examining keystores, keys, certificates, certificate requests, certificate revocation lists and more.
http://sourceforge.net/projects/portecle
http://sourceforge.net/projects/portecle
Nov 12, 2008
Free CSS Editor
CSSVista is a free Windows application for web developers that lets you edit your CSS code live in both Internet Explorer and Firefox simultaneously.
Nov 10, 2008
Oct 22, 2008
java.lang.IllegalAccessError
This is most likely due to a bad jar file or two different versions of the same jar file included in the path. Try upgrading or downloading the jar file again.
Oct 21, 2008
Linux Mounted Driver cannot remove directory error message
When running rm -rf [directory name] the following error message occurs:
rm: cannot remove directory '[directory name]': File exists
If this occurs when trying to remove a file from a mounted drive, try unmounting the drive and remounting it.
rm: cannot remove directory '[directory name]': File exists
If this occurs when trying to remove a file from a mounted drive, try unmounting the drive and remounting it.
Oct 20, 2008
How to change the default location of a Maven repository
Modify the settings.xml file to include the new repository location. Change the following line in the settings.xml file:
/path/to/local/repo
Oct 17, 2008
How Add Source to Eclipse
From the main menu at the top select Project/Properties
Select the Java Build Path on the right
Click on the Libraries tab
Browse the tree of libraries until you find the appropriate library
Expand the tree and click on Source attachment
Click the Edit button
Click the External Files button
Select the location of the source files (must be a zip or jar file)
Oct 15, 2008
Linux Commands
How to search files for specific terms:
grep -r [search term] .
How to add items such as svn, mvn, java, etc. to your PATH and set environment variables for all users:
How to add items such as svn, mvn, java, etc. to your PATH and set environment variables for all users:
Edit the /etc/profile file and then run .[space]/etc/profile with
export PATH=$PATH:/usr/java/jdk1.5.0_07/bin
How to set an environment variable:
export JAVA_HOME=/usr/java/
export ANT_HOME=/usr/ant/
How to find out where and command is installed such as java, ant, mvn:
which java
which ant
which mvn
How to stop a running program:
First determine the pid of the program:
ps -ef | grep [program name]
Then use the pid to kill the program:
kill -9 [pid]
How to search for a file:
find . -name [filename]
How to unmout a drive (Notice the command is umount and NOT UNmount):
umount [mount location]
How to clear the Java Web Start cache:
javaws -uninstall
How to view the Java Web Start Console
javaws -viewer
How to mount a drive:
mount -t [new mount name (this directory must exist)] [mount location]
mount -t /home/user/share /mnt/floppy
Oct 14, 2008
Windows Vista Connect.dll Error Message
Error message
Component file: [C:\Windows\system32\connect.dll]
Error: (0x8007277B) .
Additional Info:
Failed to detect Internet connectivity
Description
Received the following error message when trying to connect to the Internet on a Windows Vista computer.
Solutions
TCP/IP stack repair options for use with Windows Vista.
TCP/IP stack repair options for use with Windows Vista.
- Start, Programs\Accessories and right click on Command Prompt, select "Run as Administrator" to open a command prompt.
- Reset WINSOCK entries to installation defaults: netsh winsock reset catalog
- Reset IPv4 TCP/IP stack to installation defaults. netsh int ipv4 reset reset.log
- Reset IPv6 TCP/IP stack to installation defaults. netsh int ipv6 reset reset.log
- Reboot the machine.
Reinstall network/modem Driver
Uninstall the network/modem driver from Device Manager: select the items and hit Delete. Reboot.
Anti Virus and Firewall Software
Installation or Removal of Anti Virus or Firewall product can prevent the network devices from getting an IP.
Windows Update
Windows update has been known to cause this issue. Uninstall the most recent windows updates.
Jul 20, 2008
How to import data into MySQL
Description
Importing Data into MySQL
Solution
mysql [my_db_name] -u [user_name] -p[password] <>
Importing Data into MySQL
Solution
mysql [my_db_name] -u [user_name] -p[password] <>
Jun 1, 2008
How to install MySQL Server 5.0.51a on Windows Vista
Description
Installing MySQL Server 5.0.51a on Windows Vista
Solution
Installing MySQL Server 5.0.51a on Windows Vista
Solution
- Use mysql-essential-5.0.51a-win32.msi
- Download and run Resource Hacker http://www.angusj.com/resourcehacker/
- Open ...\MySQL Server 5.0\bin\MySQLInstanceConfig.exe with Resource Hacker
- Navigate to 24\1\1033
- Delete all text in the window
- Press "Compile script"
- Exit Resource Hacker and save the result (overwrite the initial MySQLInstanceConfig.exe)
- Now MySQLInstanceConfig.exe should start normally.
Mar 14, 2008
javax.servlet cannot be resolved when using Java 6
Error Message
The import javax.servlet cannot be resolved when using Java 6
Description
Java 5 uses the j2ee.jar library for javax.servelet where Java 6 uses the javaee.jar library
Solution
Add javaee.jar to the project class path. Note: Use the jdk or skd and not the jre.
In Eclipse > Project Properties > Java Build Path > Add External JARs > javaee.jar which can be found in the %JAVA_HOME%\sdk\lib
The import javax.servlet cannot be resolved when using Java 6
Description
Java 5 uses the j2ee.jar library for javax.servelet where Java 6 uses the javaee.jar library
Solution
Add javaee.jar to the project class path. Note: Use the jdk or skd and not the jre.
In Eclipse > Project Properties > Java Build Path > Add External JARs > javaee.jar which can be found in the %JAVA_HOME%\sdk\lib
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