Set the time for your Amazon EC2 instance

To verify the NTP configuration

1. From your instance, open a Command Prompt window.

2. Get the current NTP configuration by typing the following command:

   w32tm /query /configuration

   This command returns the current configuration settings for the Windows instance and will show if you're connected to the Amazon Time Sync Service.

3. (Optional) Get the status of the current configuration by typing the following command:

   w32tm /query /status

   This command returns information such as the last time the instance synced with the NTP server and the poll interval.

To change the NTP server to use the Amazon Time Sync Service

1. From the Command Prompt window, run the following command:

   w32tm /config /manualpeerlist:169.254.169.123 /syncfromflags:manual /update

2. Verify your new settings by using the following command:

   w32tm /query /configuration

   In the output that's returned, verify that NtpServer displays the 169.254.169.123 IPv4 endpoint.

To configure a direct PTP connection to the PTP hardware clock (Linux instances only)

1. Connect to your Linux instance and do the following:

   1. Install the Linux kernel driver for Elastic Network Adapter (ENA) version 2.10.0 or later.

   2. Enable the PTP hardware clock.

   For the installation instructions, see Linux kernel driver for Elastic Network Adapter (ENA) family on GitHub.

2. Verify that the /dev/ptp0 device shows up on your instance.

   [ec2-user ~]$ ls /dev/ptp0

   The following is the expected output. If /dev/ptp0 is not in the output, the ENA driver was not correctly installed. Review step 1 in this procedure for installing the driver.

   /dev/ptp0

3. Edit /etc/chrony.conf using a text editor and add the following line anywhere in the file.

   refclock PHC /dev/ptp0 poll 0 delay 0.000010 prefer

4. Restart chrony.

   [ec2-user ~]$ sudo systemctl restart chronyd

5. Verify that chrony is using the PTP hardware clock to synchronize the time on this instance.

   [ec2-user ~]$ chronyc sources

   Expected output

   MS Name/IP address         Stratum Poll Reach LastRx Last sample
   ===============================================================================
   #* PHC0                          0   0    377    1   +2ns[ +1ns] +/-   5031ns

   In the output that's returned, * indicates the preferred time source. PHC0 corresponds to the PTP hardware clock. You might need to wait a few seconds after restarting chrony for the asterisk to appear.

To set your Linux instance or device to use the public Amazon Time Sync Service using chrony or ntpd

1. Edit /etc/chrony.conf (if you use chrony) or /etc/ntp.conf (if you use ntpd) using a text editor as follows:

   1. To prevent your instance or device from trying to mix smeared and non-smeared servers, remove or comment out lines starting with server except any existing connection to the local Amazon Time Sync Service.

      Important

      If you're setting your EC2 instance to connect to the public Amazon Time Sync Service, do not remove the following line which sets your instance to connect to the local Amazon Time Sync Service. The local Amazon Time Sync Service is a more direct connection and will provide better clock accuracy. The public Amazon Time Sync Service should only be used as a backup.

      server 169.254.169.123 prefer iburst minpoll 4 maxpoll 4

   2. Add the following line to connect to the public Amazon Time Sync Service.

      pool time.aws.com iburst

2. Restart the daemon using one of the following commands.

   • chrony

     sudo service chronyd force-reload

   • ntpd

     sudo service ntp reload

To set your macOS instance or device to use the public Amazon Time Sync Service

1. Open System Preferences.

2. Choose Date & Time, and then choose the Date & Time tab.

3. To make changes, choose the lock icon, and enter your password when prompted.

4. For Set date and time automatically, enter time.aws.com.

To set your Windows instance or device to use the public Amazon Time Sync Service

1. Open the Control Panel.

2. Choose the Date and Time icon.

3. Choose the Internet Time tab. This tab is not be available if your PC is part of a domain. In this case, it will synchronize time with the domain controller. You can configure the controller to use the public Amazon Time Sync Service.

4. Choose Change settings.

5. Select the check box for Synchronize with an Internet time server.

6. Next to Server, enter time.aws.com.

To set your Windows Server instance or device to use the public Amazon Time Sync Service

• Follow Microsoft's instructions to update your registry.

To change the time zone on an AL2023 or Amazon Linux 2 instance

1. View the system's current time zone setting.

   [ec2-user ~]$ timedatectl

2. List the available time zones.

   [ec2-user ~]$ timedatectl list-timezones

3. Set the chosen time zone.

   [ec2-user ~]$ sudo timedatectl set-timezone America/Vancouver

4. (Optional) Confirm that the current time zone is updated to the new time zone by running the timedatectl command again.

   [ec2-user ~]$ timedatectl

To change the time zone on an Amazon Linux instance

1. Identify the time zone to use on the instance. The /usr/share/zoneinfo directory contains a hierarchy of time zone data files. Browse the directory structure at that location to find a file for your time zone.

   [ec2-user ~]$ ls /usr/share/zoneinfo
   Africa      Chile    GB         Indian       Mideast   posixrules  US
   America     CST6CDT  GB-Eire    Iran         MST       PRC         UTC
   Antarctica  Cuba     GMT        iso3166.tab  MST7MDT   PST8PDT     WET
   Arctic      EET      GMT0       Israel       Navajo    right       W-SU
   ...

   Some of the entries at this location are directories (such as America), and these directories contain time zone files for specific cities. Find your city (or a city in your time zone) to use for the instance.

2. Update the /etc/sysconfig/clock file with the new time zone. In this example, we use the time zone data file for Los Angeles, /usr/share/zoneinfo/America/Los_Angeles.

   1. Open the /etc/sysconfig/clock file with a text editor (such as vim or nano). You need to use sudo with your editor command because /etc/sysconfig/clock is owned by root.

      [ec2-user ~]$ sudo nano /etc/sysconfig/clock

   2. Locate the ZONE entry, and change it to the time zone file (omitting the /usr/share/zoneinfo section of the path). For example, to change to the Los Angeles time zone, change the ZONE entry to the following:

      ZONE="America/Los_Angeles"

      Note

      Do not change the UTC=true entry to another value. This entry is for the hardware clock, and does not need to be adjusted when you're setting a different time zone on your instance.

   3. Save the file and exit the text editor.

3. Create a symbolic link between /etc/localtime and the time zone file so that the instance finds the time zone file when it references local time information.

   [ec2-user ~]$ sudo ln -sf /usr/share/zoneinfo/America/Los_Angeles /etc/localtime

4. Reboot the system to pick up the new time zone information in all services and applications.

   [ec2-user ~]$ sudo reboot

5. (Optional) Confirm that the current time zone is updated to the new time zone by using the date command. The current time zone appears in the output. In the following example, the current time zone is PDT, which refers to the Los Angeles time zone.

   [ec2-user ~]$ date
   Sun Aug 16 05:45:16 PDT 2020

To change the time zone on a Windows instance

1. From your instance, open a Command Prompt window.

2. Identify the time zone to use on the instance. To get a list of time zones, use the following command:

   tzutil /l

   This command returns a list of all available time zones in the following format:

   display name
   time zone ID

3. Locate the time zone ID to assign to the instance.

4. Assign to another time zone by using the following command:

   tzutil /s "Pacific Standard Time"

   The new time zone should take effect immediately.

To set the RealTimeIsUniversal registry key

1. From the instance, open a Command Prompt window.

2. Use the following command to add the registry key:

   reg add "HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\TimeZoneInformation" /v RealTimeIsUniversal /d 1 /t REG_DWORD /f

3. If you are using a Windows Server 2008 AMI (not Windows Server 2008 R2) that was created before February 22, 2013, we recommend updating to the latest AWS Windows AMI. If you are using an AMI running Windows Server 2008 R2 (not Windows Server 2008), you must verify that the Microsoft hotfix KB2922223 is installed. If this hotfix is not installed, we recommend updating to the latest AWS Windows AMI.

4. (Optional) Verify that the instance saved the key successfully using the following command:

   reg query "HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\TimeZoneInformation" /s

   This command returns the subkeys for the TimeZoneInformation registry key. You should see the RealTimeIsUniversal key at the bottom of the list, similar to the following:

   HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\TimeZoneInformation
       Bias                            REG_DWORD     0x1e0
       DaylightBias                    REG_DWORD     0xffffffc4
       DaylightName                    REG_SZ        @tzres.dll,-211
       DaylightStart                   REG_BINARY    00000300020002000000000000000000
       StandardBias                    REG_DWORD     0x0
       StandardName                    REG_SZ        @tzres.dll,-212
       StandardStart                   REG_BINARY    00000B00010002000000000000000000
       TimeZoneKeyName                 REG_SZ        Pacific Standard Time
       DynamicDaylightTimeDisabled     REG_DWORD     0x0
       ActiveTimeBias                  REG_DWORD     0x1a4
       RealTimeIsUniversal             REG_DWORD     0x1