How this is handled is described in NIP-B7.
There is no need for the mirrored servers to be referenced in the note itself. Instead, if the media cannot be found at the original server location referenced in the note, and it is clearly a Blossom media URL given the hex string as the file name, the Nostr client will check to see if the author of the note has a kind 10063 list of Blossom servers that they use. If so, it will check to see if the same file is available from any of those servers and render it from there instead.
Dikaios1517
npub1ku…v3lhe
2025-05-16 16:32:56
in reply to nevent1q…gvnj
Author Public Key
npub1kun5628raxpm7usdkj62z2337hr77f3ryrg9cf0vjpyf4jvk9r9smv3lhePublished at
2025-05-16 16:32:56Event JSON
{
"id": "197a23898c3b2360deaa66bbecb732c3fc79fbbb64badb300920d3a4423a8728",
"pubkey": "b7274d28e3e983bf720db4b4a12a31f5c7ef262320d05c25ec90489ac99628cb",
"created_at": 1747413176,
"kind": 1,
"tags": [
[
"e",
"5d5d97f8f85625c974e2153666f297ae394c4a98449577756eb16155e8588c0c",
"",
"root",
"d49a9023a21dba1b3c8306ca369bf3243d8b44b8f0b6d1196607f7b0990fa8df"
],
[
"client",
"asknostr.site"
],
[
"p",
"d49a9023a21dba1b3c8306ca369bf3243d8b44b8f0b6d1196607f7b0990fa8df"
]
],
"content": "How this is handled is described in NIP-B7.\n\nThere is no need for the mirrored servers to be referenced in the note itself. Instead, if the media cannot be found at the original server location referenced in the note, and it is clearly a Blossom media URL given the hex string as the file name, the Nostr client will check to see if the author of the note has a kind 10063 list of Blossom servers that they use. If so, it will check to see if the same file is available from any of those servers and render it from there instead.",
"sig": "b7cd35e79522b60a97d457df772132f86b3131e4a13afe61e5d6735d0437486a73601459cb73e7c2e92c42d3fe28e95d052cf1793fbb4b234558af031e9b5857"
}