SSL protocol might be the reason here? When I did ssl test for our server, we got below information.
Changing the ssl protocol version to CURL_SSLVERSION_TLSv1 will help here?

And also curl disables sslv3 since 7.39.0

POODLE (SSLv3) Vulnerable INSECURE (more info) SSL 3: 0xa

SSLv2 is disabled by default since 7.18.1. Other SSL versions availability may vary depending on which backend libcurl has been built to use.

SSLv3 is disabled by default since 7.39.0.

Thanks,
Sasikala Raju.
-----Original Message-----
From: Daniel Stenberg [mailto:daniel_at_haxx.se]
Sent: Monday, April 11, 2016 12:33 PM
To: libcurl development <curl-library_at_cool.haxx.se>
Cc: Sasikala Raju <sasikalaraju_at_commvault.com>
Subject: Re: SSL CERT Verification

On Mon, 11 Apr 2016, Sasikala Raju wrote:

> While establishing connection for https protocol , facing the issue with
> certification although ca bundle have cert required. It's happening only in
> customer environment. Whereas all test machines are able to successfully
> verify the certificate.
>
> Root Certificate required is Entrust Root Certification Authority - G2 and
> it does present in CA bundle provided. CA Bundle used in both machines is
> same. Is there any reason its failing only in specific environment though CA
> bundle is same?

Are you using the same OpenSSL and libcurl versions in both setups?

-- 
  / daniel.haxx.se
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