常見問題
透過集合功能整理內容
你可以依據偏好儲存及分類內容。
一般
什麼是 Google Public NTP？
Google Public NTP 是免費的全域時間服務，可讓您與 Google 的原子鐘同步。這個函式會實作閏秒模糊化，順暢處理閏秒，不會造成中斷。
Google 為何要開發 NTP 服務？
我們非常重視時間同步，而 NTP 是目前最廣為使用的時間同步通訊協定。一般來說，NTP 的運作效果非常好。不過，我們知道許多 NTP 伺服器不會正確發布閏秒，而且即使透過 NTP 發布，許多系統也不會正確處理閏秒。
自 2008 年起，我們在內部透過「抹除」閏秒的方式解決這個問題，也就是在閏秒前後的幾小時內，逐步進行時間變更。這項功能效果非常好。我們推出 Google Compute Engine 時，開始透過 NTP 為客戶的虛擬機器提供時間延遲。Google 公開 NTP 可讓全球連上網際網路的裝置使用這項服務。
Google 員工是否使用 Google Public NTP？
可以。我們使用 Google 公開 NTP 設定筆電、工作站、路由器和許多其他裝置的時鐘。Google Fiber 客戶也會使用這項服務。
Google Public NTP 是否有任何跨產品依附元件？
否。Google Public NTP 是獨立服務。
我需要有 Google 帳戶才能使用 Google 公開 NTP 嗎？
不用
使用與支援
如何使用 Google Public NTP？
將裝置設定為使用 NTP 伺服器 time.google.com，或四部伺服器 time1.google.com、time2.google.com、time3.google.com 和 time4.google.com。如果無法設定多部伺服器，系統會自動選取附近的適當 Google 伺服器。time.google.com
我們針對許多常見的作業系統，提供詳細操作說明。
我目前使用其他 NTP 服務，我也可以使用 Google 公開 NTP 嗎？
建議您不要混用經過塗抹和未經塗抹的 NTP 伺服器。閏秒期間的結果可能難以預測。
Google Public NTP 適用於所有類型的連網裝置嗎？
可以。凡是支援 NTP 或 SNTP 3 或 4 版的裝置，都可以使用 Google 公開 NTP。如果發現 Google Public NTP 無法正常運作，請告訴我們。
Google Public NTP 適用於哪些國家/地區？
全球各地的網路使用者都能使用這項服務，但實際體驗可能因所在位置而異。
Google Public NTP 是否適用於所有網際網路服務供應商？
只要您有權變更 NTP 設定，Google Public NTP 應該就能與大多數 ISP 搭配運作。
我是否需要使用全部四個 Google 公開 NTP 伺服器名稱？
不會。你可以使用 time.google.com，系統會自動將你導向附近的伺服器。
指定伺服器名稱的順序是否會影響結果？
不會，順序沒有影響。
這項服務的服務水準協議為何？
我們目前未提供這項服務的服務水準協議。
《服務條款》內容為何？
Google Public NTP 適用《Google API 服務條款》。
我經營網際網路服務供應商 (ISP) 或企業網路。我可以將所有使用者重新導向至 Google 公共 NTP 嗎？
可以。我們可以接受來自任意數量 NTP 用戶端的流量。但目前 Google Public NTP 服務不提供服務水準協議。
我可以在商業專案或產品中使用 Google Public NTP 嗎？
可以，但須遵守我們的《服務條款》。Google 公開 NTP 是一項不提供服務水準協議的服務，我們不會就可用性或準確度做出任何承諾。
我為機構執行 NTP 伺服器。我可以將其同步至 Google Public NTP 嗎？
是。
我可以在 Google Compute Engine 執行個體中使用 Google 公開 NTP 嗎？
可以，但使用metadata.google.internal
(詳細指示)可獲得更精準的結果。
該虛擬伺服器的時間服務會與 Google Public NTP 相同。
我可以在其他雲端服務供應商執行的虛擬機器上使用 Google 公開 NTP 嗎？
是。
如何取得 Google Public NTP 團隊的支援？
建議您加入 Google 群組，接收團隊的最新消息，並提出任何問題。如果遇到問題並想回報，請參閱「回報問題」一文瞭解相關程序。
技術
可以提供更多有關抹片檢查結果的詳細資料嗎？
是的，詳情請參閱這篇文章。
Google 公開 NTP 如何使用 Leap Indicator (LI) 欄位？
Google 公開 NTP 一律會將 LI 欄位設為 0，因為閏秒是透過抹除在伺服器端套用。
您的伺服器目前位於何處？
Google Public NTP 伺服器位於北美洲、歐洲和亞洲的數個資料中心。
Google Public NTP 是否支援 IPv6？
是。
Google Public NTP 是否支援 Autokey 或 NTS？
不用
如果您對安全時間分配感興趣，也可以考慮使用 Chrome 團隊的實驗性專案 Roughtime。Roughtime 目前還不是高精確度的時間服務，但這項實驗旨在提供可信賴的時間。
Google Public NTP 是否支援 SNTP 用戶端？
是。
Google Public NTP 是否支援 Windows Time 用戶端？
是。
Google Public NTP 是否支援模式 6 或模式 7 控制訊息？
不會，這項服務不會回應控制訊息，例如 ntpq 或 ntpdc 傳送的訊息。
Google Public NTP 是否可能遭到濫用，用於 NTP 放大攻擊？
不會。
NTP 放大攻擊會使用 NTP 控制訊息。Google Public NTP 只會回應用戶端時間查詢，並傳送大小與要求類似的回覆。
除非另有註明，否則本頁面中的內容是採用創用 CC 姓名標示 4.0 授權，程式碼範例則為阿帕契 2.0 授權。詳情請參閱《Google Developers 網站政策》。Java 是 Oracle 和/或其關聯企業的註冊商標。
上次更新時間：2025-07-25 (世界標準時間)。
[[["容易理解","easyToUnderstand","thumb-up"],["確實解決了我的問題","solvedMyProblem","thumb-up"],["其他","otherUp","thumb-up"]],[["缺少我需要的資訊","missingTheInformationINeed","thumb-down"],["過於複雜/步驟過多","tooComplicatedTooManySteps","thumb-down"],["過時","outOfDate","thumb-down"],["翻譯問題","translationIssue","thumb-down"],["示例/程式碼問題","samplesCodeIssue","thumb-down"],["其他","otherDown","thumb-down"]],["上次更新時間：2025-07-25 (世界標準時間)。"],[[["\u003cp\u003eGoogle Public NTP is a free, global time service that synchronizes devices to Google's atomic clocks using leap smear for smooth leap second handling.\u003c/p\u003e\n"],["\u003cp\u003eIt is available worldwide to any device supporting NTP or SNTP versions 3 or 4, accessible by configuring devices to use \u003ccode\u003etime.google.com\u003c/code\u003e or the four individual server addresses.\u003c/p\u003e\n"],["\u003cp\u003eGoogle Public NTP is an independent service covered by Google API Terms of Service, and while suitable for commercial use, it is offered without an SLA.\u003c/p\u003e\n"],["\u003cp\u003eGoogle smears the leap second over a longer period, so mixing Google Public NTP with other non-smeared NTP services is not recommended.\u003c/p\u003e\n"],["\u003cp\u003eSupport and updates are available through the Google Groups dedicated to Google Public NTP, and detailed technical information, including leap smear details, can be found on the associated webpages.\u003c/p\u003e\n"]]],["Google Public NTP is a free, global time service using Google's atomic clocks, designed to smoothly handle leap seconds through a \"leap smear\" method. Users can synchronize devices by configuring them to `time.google.com` or `time[1-4].google.com`. It is an independent service that supports NTP/SNTP v3/4 clients, IPv6, and is accessible worldwide. The service doesn't support Autokey, NTS, or control messages, and is safe from NTP amplification attacks. There is no SLA, but traffic from all users is accepted.\n"],null,["# Frequently Asked Questions\n\nGeneral\n-------\n\n### What is Google Public NTP?\n\nGoogle Public NTP is a free, global time service that you can use to synchronize\nto Google's atomic clocks. It implements the [leap smear](/time/smear) to\nsmoothly handle leap seconds without disruptions.\n\n### Why is Google working on an NTP service?\n\nTimekeeping is important to us, and NTP is by far the most widely used time\nsynchronization protocol. In general, NTP works very well. However, we know that\n[many NTP servers do not correctly announce leap seconds](https://scholar.google.com/scholar?q=10.1007%2F978-3-319-30505-9_29),\nand that even when they are announced through NTP,\n[many systems do not correctly handle the leap](https://www.wired.com/2012/07/leap-second-glitch-explained/).\n\nSince 2008, we've addressed this problem internally by \"smearing\" the leap\nsecond, stretching out the change across the hours around the leap. This has\nworked very well. When we launched Google Compute Engine, we started providing\nsmeared time via NTP to customers' virtual machines. Google Public NTP makes\nthis available globally to Internet-connected devices.\n\n### Are Googlers using Google Public NTP?\n\nYes. We use Google Public NTP to set the clocks on our laptops, workstations,\nrouters, and many other devices. It's also used by Google Fiber customers.\n\n### Are there any cross-product dependencies with Google Public NTP?\n\nNo. Google Public NTP is an independent service.\n\n### Do I need a Google Account to use Google Public NTP?\n\nNo.\n\nUse and support\n---------------\n\n### How do I use Google Public NTP?\n\nConfigure your devices to use either the NTP server `time.google.com` or the\nfour servers `time1.google.com`, `time2.google.com`, `time3.google.com`, and\n`time4.google.com`. If you cannot configure multiple servers, `time.google.com`\nwill automatically select an appropriate Google server nearby.\n\nWe have [detailed instructions](/time/guides) for many popular operating\nsystems.\n\n### I am using another NTP service now. Can I also use Google Public NTP?\n\nWe recommend that you do not mix smeared and non-smeared NTP servers. The\nresults during a leap second may be unpredictable.\n\n### Is Google Public NTP suitable for all types of Internet-enabled devices?\n\nYes. Google Public NTP can be used on any device that supports NTP or SNTP\nversions 3 or 4. If you find any situation where Google Public NTP does not work\nwell, [let us know](/time/support#issues).\n\n### In which countries is Google Public NTP available?\n\nIt is available to Internet users around the world, though your experience may\nvary greatly based on your specific location.\n\n### Does Google Public NTP work with all ISPs?\n\nGoogle Public NTP should work with most ISPs, assuming you have access to change\nyour NTP settings.\n\n### Do I need to use all four Google Public NTP server names?\n\nNo. You can use `time.google.com` to be directed automatically to a nearby\nserver.\n\n### Does it matter in what order I specify the server names?\n\nNo, the order does not matter.\n\n### What is the SLA for the service?\n\nWe are not providing an SLA for this service at this time.\n\n### What are the Terms of Service?\n\nGoogle Public NTP is covered by the\n[Google API Terms of Service](https://developers.google.com/terms/).\n\n### I'm running an ISP or enterprise network. Can I redirect all my users to Google Public NTP?\n\nYes. We can accept traffic from any number of NTP clients. But at this time,\nGoogle Public NTP is a service without an SLA.\n\n### Can I use Google Public NTP for my commercial project or products?\n\nYes, subject to our [terms of service](#tos). Google Public NTP is a service\nwithout an SLA; we do not provide any commitments about availability or\naccuracy.\n\n### I run an NTP server for my organization. Can I synchronize it to Google Public NTP?\n\nYes.\n\n### Can I use Google Public NTP from Google Compute Engine instances?\n\nYes, but you will get better results by using `metadata.google.internal`\n([detailed instructions](https://cloud.google.com/compute/docs/instances/managing-instances#configure_ntp_for_your_instances)).\nTime service from that virtual server is smeared identically to Google Public\nNTP.\n\n### Can I use Google Public NTP from virtual machines running at other cloud providers?\n\nYes.\n\n### How can I get support from the Google Public NTP team?\n\nWe recommend that you join our [Google Groups](/time/support#groups) to get\nupdates from the team and ask any questions you have. If you are encountering a\nproblem and would like to report it, see\n[Reporting issues](/time/support#issues) for procedures.\n\nTechnical\n---------\n\n### Are there more details about the leap smear?\n\nYes, we have [more information here](/time/smear).\n\n### How does Google Public NTP use the Leap Indicator (LI) field?\n\nGoogle Public NTP always sets the LI field to 0, because the leap second is\napplied on the server side using the smear.\n\n### Where are your servers currently located?\n\nGoogle Public NTP servers are available in several of our data centers in North\nAmerica, Europe, and Asia.\n\n### Does Google Public NTP support IPv6?\n\nYes.\n\n### Does Google Public NTP support Autokey or NTS?\n\nNo.\n\nIf you are interested in secure time distribution, you may also want to look at\n[Roughtime](https://roughtime.googlesource.com/roughtime), an experimental\nproject from the Chrome team. Roughtime is not yet a high-precision time\nservice, but it is an experiment in providing trusted time.\n\n### Does Google Public NTP support SNTP clients?\n\nYes.\n\n### Does Google Public NTP support Windows Time clients?\n\nYes.\n\n### Does Google Public NTP support mode 6 or mode 7 control messages?\n\nNo, it will not respond to control messages, such as those sent by `ntpq` or\n`ntpdc`.\n\n### Could Google Public NTP be abused for NTP amplification attacks?\n\nNo.\n[NTP amplification attacks](https://blog.cloudflare.com/understanding-and-mitigating-ntp-based-ddos-attacks/)\nuse NTP control messages. Google Public NTP responds only to client time\nqueries, and sends replies that are similar in size to the request."]]
