diff --git a/ca.conf.sample b/ca.conf.sample
index d81a8e9..0324699 100644
--- a/ca.conf.sample
+++ b/ca.conf.sample
@@ -1,34 +1,12 @@
 {
-  "ca-list":
+  "ca-prefix": "/example",
+  "issuing-freshness": "720",
+  "validity-period": "360",
+  "ca-info": "An example NDNCERT CA",
+  "probe": "[JSON attribute]:[JSON attribute]:[...] Example: email:UID"
+  "supported-challenges":
   [
-    {
-        "ca-prefix": "/ndn",
-        "issuing-freshness": "720",
-        "validity-period": "360",
-        "ca-info": "NDN Testbed CA",
-
-        "probe": "email",
-
-        "targeted-list": "Use your email address (edu preferred) as input",
-        "related-ca-list":
-        [
-          { "ca-prefix": "/ndn/edu/arizona" },
-          { "ca-prefix": "/ndn/edu/memphis" }
-        ],
-
-        "supported-challenges":
-        [
-            { "type": "PIN" }
-        ]
-    },
-    {
-        "ca-prefix": "/example",
-        "issuing-freshness": "720",
-        "validity-period": "360",
-        "supported-challenges":
-        [
-            { "type": "PIN" }
-        ]
-    }
+    { "type": "PIN" },
+    { "type": "Email" }
   ]
-}
\ No newline at end of file
+}
diff --git a/client.conf.sample b/client.conf.sample
index a0de72a..7e7d316 100644
--- a/client.conf.sample
+++ b/client.conf.sample
@@ -2,10 +2,9 @@
   "ca-list":
   [
     {
-        "ca-prefix": "/ndn/CA",
-        "ca-info": "NDN Testbed CA",
+        "ca-prefix": "/example",
+        "ca-info": "An example NDNCERT CA",
         "probe": "email",
-        "target-list": "Use your email address (edu preferred) as input",
         "certificate": "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"
     }
   ],
diff --git a/src/ca-module.cpp b/src/ca-module.cpp
index 1794528..74985aa 100644
--- a/src/ca-module.cpp
+++ b/src/ca-module.cpp
@@ -195,18 +195,24 @@
   if (probeTokenStr != "") {
     try {
       std::stringstream ss(probeTokenStr);
-      probeToken = io::load<security::v2::Certificate>(ss);
+      probeToken = io::load<Data>(ss);
     }
     catch (const std::exception& e) {
       _LOG_ERROR("Unrecognized probe token " << e.what());
       return;
     }
   }
-  if (probeToken != nullptr) {
+  if (probeToken == nullptr && m_config.m_probe != "") {
+    // the CA requires PROBE before NEW
+    _LOG_ERROR("CA requires PROBE but no PROBE token is found in NEW Interest.");
+    return;
+  }
+  else if (probeToken != nullptr) {
+    // check whether the carried probe token is a PROBE Data packet
     Name prefix = m_config.m_caName;
     prefix.append("CA").append("_PROBE");
     if (!prefix.isPrefixOf(probeToken->getName())) {
-      // the carried probe token is not a Probe Data packet
+      _LOG_ERROR("Carried PROBE token is not a valid PROBE Data packet.");
       return;
     }
   }
@@ -231,7 +237,7 @@
     const auto& key = pib.getIdentity(m_config.m_caName).getDefaultKey();
     const auto& caCert = key.getDefaultCertificate();
     if (!security::verifySignature(*probeToken, caCert)) {
-      _LOG_TRACE("Token with bad signature.");
+      _LOG_TRACE("PROBE Token with bad signature.");
       return;
     }
   }
diff --git a/tests/unit-tests/ca-config.t.cpp b/tests/unit-tests/ca-config.t.cpp
index 78aa9da..0e53dff 100644
--- a/tests/unit-tests/ca-config.t.cpp
+++ b/tests/unit-tests/ca-config.t.cpp
@@ -38,7 +38,7 @@
   BOOST_CHECK_EQUAL(config.m_caName.toUri(), "/ndn");
   BOOST_CHECK_EQUAL(config.m_freshnessPeriod, time::seconds(720));
   BOOST_CHECK_EQUAL(config.m_validityPeriod, time::days(360));
-  BOOST_CHECK_EQUAL(config.m_probe, "input email address");
+  BOOST_CHECK_EQUAL(config.m_probe, "");
   BOOST_CHECK_EQUAL(config.m_caInfo, "ndn testbed ca");
 }
 
diff --git a/tests/unit-tests/ca-module.t.cpp b/tests/unit-tests/ca-module.t.cpp
index a3e5f01..a3fa150 100644
--- a/tests/unit-tests/ca-module.t.cpp
+++ b/tests/unit-tests/ca-module.t.cpp
@@ -108,7 +108,7 @@
       auto contentJson = ClientModule::getJsonFromData(response);
       auto caItem = ClientConfig::extractCaItem(contentJson);
       BOOST_CHECK_EQUAL(caItem.m_caName.toUri(), "/ndn");
-      BOOST_CHECK_EQUAL(caItem.m_probe, "input email address");
+      BOOST_CHECK_EQUAL(caItem.m_probe, "");
       BOOST_CHECK_EQUAL(caItem.m_anchor.wireEncode(), cert.wireEncode());
       BOOST_CHECK_EQUAL(caItem.m_caInfo, "ndn testbed ca");
     });
@@ -195,6 +195,7 @@
 
   util::DummyClientFace face(m_io, {true, true});
   CaModule ca(face, m_keyChain, "tests/unit-tests/ca.conf.test");
+  ca.m_config.m_probe = "email";
   advanceClocks(time::milliseconds(20), 60);
 
   ClientModule client(m_keyChain);
@@ -203,7 +204,7 @@
   item.m_anchor = cert;
   client.getClientConf().m_caItems.push_back(item);
 
-  auto data = make_shared<Data>(Name("/ndn/CA/probe/123"));
+  auto data = make_shared<Data>(Name("/ndn/CA/_PROBE/123"));
   m_keyChain.sign(*data, signingByIdentity(ca.m_config.m_caName));
 
   auto interest = client.generateNewInterest(time::system_clock::now(),
diff --git a/tests/unit-tests/ca.conf.test b/tests/unit-tests/ca.conf.test
index 15b497f..8acd23c 100644
--- a/tests/unit-tests/ca.conf.test
+++ b/tests/unit-tests/ca.conf.test
@@ -3,8 +3,6 @@
   "issuing-freshness": "720",
   "validity-period": "360",
   "ca-info": "ndn testbed ca",
-
-  "probe": "input email address",
   "supported-challenges":
   [
       { "type": "PIN" }
diff --git a/tests/unit-tests/client-config.t.cpp b/tests/unit-tests/client-config.t.cpp
index 5f7c3a5..1026ad8 100644
--- a/tests/unit-tests/client-config.t.cpp
+++ b/tests/unit-tests/client-config.t.cpp
@@ -35,9 +35,9 @@
   BOOST_CHECK_EQUAL(config.m_caItems.size(), 2);
 
   const auto& item = config.m_caItems.front();
-  BOOST_CHECK_EQUAL(item.m_caName.toUri(), "/ndn/edu/ucla/CA");
+  BOOST_CHECK_EQUAL(item.m_caName.toUri(), "/ndn/edu/ucla");
   BOOST_CHECK_EQUAL(item.m_caInfo, "UCLA's ceritificate authority, located in BH4805.");
-  BOOST_CHECK_EQUAL(item.m_probe, "Please use your email address to apply a namespace first. UCLA email is preferred.");
+  BOOST_CHECK_EQUAL(item.m_probe, "email");
   BOOST_CHECK_EQUAL(item.m_anchor.getName().toUri(),
                     "/ndn/site1/KEY/%11%BC%22%F4c%15%FF%17/self/%FD%00%00%01Y%C8%14%D9%A5");
 
@@ -62,7 +62,7 @@
   config.removeCaItem(Name("/test"));
   BOOST_CHECK_EQUAL(config.m_caItems.size(), 2);
   lastItem = config.m_caItems.back();
-  BOOST_CHECK_EQUAL(lastItem.m_caName.toUri(), "/ndn/edu/ucla/zhiyi/CA");
+  BOOST_CHECK_EQUAL(lastItem.m_caName.toUri(), "/ndn/edu/ucla/zhiyi");
 }
 
 BOOST_AUTO_TEST_SUITE_END() // TestClientConfig
diff --git a/tests/unit-tests/client.conf.test b/tests/unit-tests/client.conf.test
index c75d4d1..903c2bd 100644
--- a/tests/unit-tests/client.conf.test
+++ b/tests/unit-tests/client.conf.test
@@ -1,18 +1,18 @@
 {
   "ca-list":
   [
-    {   
-        "ca-prefix": "/ndn/edu/ucla/CA",
+    {
+        "ca-prefix": "/ndn/edu/ucla",
         "ca-info": "UCLA's ceritificate authority, located in BH4805.",
-        "probe": "Please use your email address to apply a namespace first. UCLA email is preferred.",
+        "probe": "email",
         "certificate": "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"
-    },  
-        {   
-        "ca-prefix": "/ndn/edu/ucla/zhiyi/CA",
+    },
+    {
+        "ca-prefix": "/ndn/edu/ucla/zhiyi",
         "ca-info": "Zhiyi's own ceritificate authority",
-        "probe": "true",
+        "probe": "email",
         "certificate": "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"
-    }   
+    }
   ],
   "local-ndncert-anchor": "/usr/local/etc/ndncert/anchor.key"
 }
\ No newline at end of file