Can any1 help me to solve this error.

com.sforce.ws.ConnectionException: Failed to send request to https://login.salesforce.com/services/Soap/c/24.0/0DF90000000PX8r
    at com.sforce.ws.transport.SoapConnection.send(SoapConnection.java:120)
    at com.sforce.soap.enterprise.EnterpriseConnection.login(EnterpriseConnection.java:1)
    at com.sforce.soap.enterprise.EnterpriseConnection.<init>(EnterpriseConnection.java:1)
    at wsc.QuickstartApiSample.login(QuickstartApiSample.java:78)
    at wsc.QuickstartApiSample.main(QuickstartApiSample.java:36)
Caused by: java.net.UnknownHostException: login.salesforce.com
    at java.net.PlainSocketImpl.connect(Unknown Source)
    at java.net.SocksSocketImpl.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at com.sun.net.ssl.internal.ssl.SSLSocketImpl.connect(Unknown Source)
    at com.sun.net.ssl.internal.ssl.BaseSSLSocketImpl.connect(Unknown Source)
    at sun.net.NetworkClient.doConnect(Unknown Source)
    at sun.net.www.http.HttpClient.openServer(Unknown Source)
    at sun.net.www.http.HttpClient.openServer(Unknown Source)
    at sun.net.www.protocol.https.HttpsClient.<init>(Unknown Source)
    at sun.net.www.protocol.https.HttpsClient.New(Unknown Source)
    at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.getNewHttpClient(Unknown Source)
    at sun.net.www.protocol.http.HttpURLConnection.plainConnect(Unknown Source)
    at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(Unknown Source)
    at sun.net.www.protocol.http.HttpURLConnection.getOutputStream(Unknown Source)
    at sun.net.www.protocol.https.HttpsURLConnectionImpl.getOutputStream(Unknown Source)
    at com.sforce.ws.transport.JdkHttpTransport.connectRaw(JdkHttpTransport.java:133)
    at com.sforce.ws.transport.JdkHttpTransport.connectLocal(JdkHttpTransport.java:97)
    at com.sforce.ws.transport.JdkHttpTransport.connectLocal(JdkHttpTransport.java:92)
    at com.sforce.ws.transport.JdkHttpTransport.connect(JdkHttpTransport.java:88)
    at com.sforce.ws.transport.SoapConnection.send(SoapConnection.java:94)
    ... 4 more