404; create it with POST /nmsconfig. The write is published over the service bus (SBUS), so 202 means accepted, not yet applied. synchronous=yes waits until every server that answers holds the new value, for up to synchronous-timeout milliseconds (default 2000, at most 5000), then answers 200 with one row per server. config-applied is yes (holds it), no (not seen there yet, which never means rejected), or unknown (the server did not answer). Replication is batched, so a short timeout often reports no.config-value on a credential-shaped key looks like a mask (**** or Ex*****01), it is left out, so every server keeps its own stored value, and a config-geo sent with it is still applied. With nothing left to change, the answer is 202 and nothing is published.config-server writes one server only, with no replication. Name a core server's hostname and only that server's row changes: the server that takes the request writes its own row, or forwards the write to the named server. Two things follow:config-in-sync: no.config-server out, or sending *, all, any, or geo, replicates to every server. A hostname that is not in the cluster returns 404. A forwarded write that gets no answer returns 502: read the key before retrying, because the server may have applied it. An inventory entry that is not a valid hostname is never contacted, and a write naming it returns 502.Authorization: Bearer ********************synchronous=yes: one row per core server, reporting whether it holds the written value. With config-server, only that server is reported.curl --location --request PUT 'https://awqacore01.crexendocloud.com/ns-api/v2/nmsconfig/SMTP_HOST?synchronous=undefined&synchronous-timeout=undefined&verify=yes&verify-timeout=3000' \
--header 'Authorization: Bearer <token>' \
--header 'Content-Type: application/json' \
--data '{
"config-value": "smtp.example.com"
}'[
{
"config-name": "SMTP_HOST",
"config-server": "core1.example.com",
"config-applied": "yes"
},
{
"config-name": "SMTP_HOST",
"config-server": "core2.example.com",
"config-applied": "no"
}
]