# Get nonce

JWS header must contain a fresh nonce, received from the ACME server. Each nonce value can be used only once, and only within a limited period of time (usually 1 hour). To acquire a new nonce value, send a HEAD or a GET request to the newNonce URL. ACME server shall return an empty response with a newly generated nonce string in a Replay-Nonce header.

```
HEAD https://stica.peeringhub.io/acme/new-nonce

HTTP/1.1 200 OK
Replay-Nonce: ABECF2EDB773493ABC9C6E000420DBEC
Content-Length: 0
```

ACME server should generate a fresh nonce value in reply to every HTTP request, described in this document. The new nonce value should be included into Replay-Nonce header.


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# Agent Instructions: Querying This Documentation

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```
GET https://doc.peeringhub.io/guides/generating-certificate/acme-protocol-reference/get-nonce.md?ask=<question>
```

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Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.