Why does one server default to a TLSv1.2 connection and the other does not?
By default, curl
will negotiate with the server, and will use the highest version that both curl
and the server support. So if the connection uses different TLS versions, you likely have different versions of curl
on the servers. As you write that the version reported by curl is the same, you should also check the version of "libcurl", the shared library that is used by curl
- this might also be different.
Most likely one of the servers uses a fairly old version of curl
or libcurl - curl has supported TLS 1.3 since 2016 (v7.52, I believe), and TLS 1.2 since 2012 (v7.28).
I have 2 servers that both run curl 7.29.0 and CentOS 7.
Note that curl 7.29 is fairly old (released February 2013), so an upgrade is a good idea anyway.