When configuring Kerberos authentication for Databases in TIBCO Data Virtualization, users may notice "Receive timed out" exception while performing Test connection on the data source and stack with "datagram" error. This occurs when Java program is trying to connect using UDP (User Datagram Protocol) instead of TCP (Transmission Control Protocol).
The following Error Stack is logged under cs_server.log.

Caused by: javax.security.auth.login.LoginException: Receive timed out
        at com.sun.security.auth.module.Krb5LoginModule.attemptAuthentication(Krb5LoginModule.java:808)
        at com.sun.security.auth.module.Krb5LoginModule.login(Krb5LoginModule.java:617)     
Caused by: java.net.SocketTimeoutException: Receive timed out
        at java.net.PlainDatagramSocketImpl.receive0(Native Method)
        at java.net.AbstractPlainDatagramSocketImpl.receive(AbstractPlainDatagramSocketImpl.java:143)
        at java.net.DatagramSocket.receive(DatagramSocket.java:812)
        at sun.security.krb5.internal.UDPClient.receive(NetClient.java:206)

Configuring krb5.conf file in TIBCO Data Virtualization to use TCP instead of UDP.

To ensure the connection uses TCP, add the udp_preference_limit = 1 parameter in krb5.conf file under etc/krb5.conf. This will resolve "Receive timed out" error.

https://docs.centrify.com/en/css/2018-html/index.html#page/Configuration_and_tuning_reference/krb5.udp.preference.limit.41.html