Have seen this fail ONLY on Solaris sparc 64bit (JPRT). Passed on all other platforms.
Filing this just for the record.

--------------------------------------------------
TEST: sun/security/krb5/auto/BadKdc4.java
JDK under test: (/tmp/jprt/T1/T/172836.ohair/testproduct/solaris_sparcv9_5.10-product)
java version "1.7.0-201005081728.ohair.jdk"
Java(TM) SE Runtime Environment (build 1.7.0-201005081728.ohair.jdk-jprtadm_2010_05_08_11_15-b00)
Java HotSpot(TM) Server VM (build 18.0-b04, mixed mode)

ACTION: build -- Passed. Build successful
REASON: Named class compiled on demand
TIME: 1.203 seconds
messages:
command: build BadKdc4
reason: Named class compiled on demand
elapsed time (seconds): 1.203

ACTION: compile -- Passed. Compilation successful
REASON: .class file out of date or does not exist
TIME: 1.201 seconds
messages:
command: compile /tmp/jprt/T1/T/172836.ohair/source/test/sun/security/krb5/auto/BadKdc4.java
reason: .class file out of date or does not exist
elapsed time (seconds): 1.201
STDOUT:
STDERR:

ACTION: main -- Failed. Execution failed: `main' threw exception: javax.security.auth.login.LoginException: Identifier doesn't match expected value (906)
REASON: User specified action: run main/timeout=300 BadKdc4
TIME: 84.506 seconds
messages:
command: main BadKdc4
reason: User specified action: run main/timeout=300 BadKdc4
elapsed time (seconds): 84.506
STDOUT:
Config name: alternative-krb5.conf
>>> KdcAccessibility: reset
>>> KdcAccessibility: reset
Start KDC on 34095
----------------- TEST -----------------
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:15895, timeout=2000,Attempt =1, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:15895, timeout=2000,Attempt =2, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:15895, timeout=2000,Attempt =3, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:25069, timeout=2000,Attempt =1, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:25069, timeout=2000,Attempt =2, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:25069, timeout=2000,Attempt =3, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:34095, timeout=2000,Attempt =1, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:15895, timeout=2000,Attempt =1, #bytes=214
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:15895, timeout=2000,Attempt =2, #bytes=214
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:15895, timeout=2000,Attempt =3, #bytes=214
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:25069, timeout=2000,Attempt =1, #bytes=214
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:25069, timeout=2000,Attempt =2, #bytes=214
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:25069, timeout=2000,Attempt =3, #bytes=214
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:34095, timeout=2000,Attempt =1, #bytes=214
----------------- TEST -----------------
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:15895, timeout=2000,Attempt =1, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:15895, timeout=2000,Attempt =2, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:15895, timeout=2000,Attempt =3, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:25069, timeout=2000,Attempt =1, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:25069, timeout=2000,Attempt =2, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:25069, timeout=2000,Attempt =3, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:34095, timeout=2000,Attempt =1, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:15895, timeout=2000,Attempt =1, #bytes=214
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:15895, timeout=2000,Attempt =2, #bytes=214
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:15895, timeout=2000,Attempt =3, #bytes=214
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:25069, timeout=2000,Attempt =1, #bytes=214
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:25069, timeout=2000,Attempt =2, #bytes=214
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:25069, timeout=2000,Attempt =3, #bytes=214
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:34095, timeout=2000,Attempt =1, #bytes=214
Config name: alternative-krb5.conf
>>> KdcAccessibility: reset
----------------- TEST -----------------
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:15895, timeout=2000,Attempt =1, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:15895, timeout=2000,Attempt =2, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:15895, timeout=2000,Attempt =3, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:25069, timeout=2000,Attempt =1, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:25069, timeout=2000,Attempt =2, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:25069, timeout=2000,Attempt =3, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:34095, timeout=2000,Attempt =1, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:15895, timeout=2000,Attempt =1, #bytes=214
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:15895, timeout=2000,Attempt =2, #bytes=214
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:15895, timeout=2000,Attempt =3, #bytes=214
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:25069, timeout=2000,Attempt =1, #bytes=214
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:25069, timeout=2000,Attempt =2, #bytes=214
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:25069, timeout=2000,Attempt =3, #bytes=214
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:34095, timeout=2000,Attempt =1, #bytes=214
Start KDC on 25069
STDERR:
javax.security.auth.login.LoginException: Identifier doesn't match expected value (906)
at com.sun.security.auth.module.Krb5LoginModule.attemptAuthentication(Krb5LoginModule.java:732)
at com.sun.security.auth.module.Krb5LoginModule.login(Krb5LoginModule.java:557)
at Context.fromUserPass(Context.java:134)
at BadKdc.test(BadKdc.java:93)
at BadKdc.go(BadKdc.java:72)
at BadKdc4.main(BadKdc4.java:39)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:613)
at com.sun.javatest.regtest.MainWrapper$MainThread.run(MainWrapper.java:94)
at java.lang.Thread.run(Thread.java:717)
Caused by: KrbException: Identifier doesn't match expected value (906)
at sun.security.krb5.internal.KRBError.init(KRBError.java:366)
at sun.security.krb5.internal.KRBError.<init>(KRBError.java:197)
at sun.security.krb5.KrbAsRep.<init>(KrbAsRep.java:62)
at sun.security.krb5.KrbAsReq.getReply(KrbAsReq.java:469)
at sun.security.krb5.Credentials.sendASRequest(Credentials.java:427)
at sun.security.krb5.Credentials.acquireTGT(Credentials.java:399)
at com.sun.security.auth.module.Krb5LoginModule.attemptAuthentication(Krb5LoginModule.java:698)
... 11 more

JavaTest Message: Test threw exception: javax.security.auth.login.LoginException: Identifier doesn't match expected value (906)
JavaTest Message: shutting down test

STATUS:Failed.`main' threw exception: javax.security.auth.login.LoginException: Identifier doesn't match expected value (906)

TEST RESULT: Failed. Execution failed: `main' threw exception: javax.security.auth.login.LoginException: Identifier doesn't match expected value (906)
--------------------------------------------------
Also failed on Linux -server 32bit (Fedora 9)

--------------------------------------------------
TEST: sun/security/krb5/auto/BadKdc3.java
JDK under test: (/tmp/jprt/P1/T/154735.ohair/testproduct/linux_i586_2.6-product)
java version "1.7.0-201005091547.ohair.jdk"
Java(TM) SE Runtime Environment (build 1.7.0-201005091547.ohair.jdk-jprtadm_2010_05_09_08_52-b00)
Java HotSpot(TM) Server VM (build 18.0-b04, mixed mode)

ACTION: build -- Passed. Build successful
REASON: Named class compiled on demand
TIME: 0.721 seconds
messages:
command: build BadKdc3
reason: Named class compiled on demand
elapsed time (seconds): 0.721

ACTION: compile -- Passed. Compilation successful
REASON: .class file out of date or does not exist
TIME: 0.721 seconds
messages:
command: compile /tmp/jprt/P1/T/154735.ohair/source/test/sun/security/krb5/auto/BadKdc3.java
reason: .class file out of date or does not exist
elapsed time (seconds): 0.721
STDOUT:
STDERR:

ACTION: main -- Failed. Execution failed: `main' threw exception: java.lang.ArrayIndexOutOfBoundsException: 16
REASON: User specified action: run main/timeout=300 BadKdc3
TIME: 16.37 seconds
messages:
command: main BadKdc3
reason: User specified action: run main/timeout=300 BadKdc3
elapsed time (seconds): 16.37
STDOUT:
Config name: alternative-krb5.conf
>>> KdcAccessibility: reset
>>> KdcAccessibility: reset
Start KDC on 39493
----------------- TEST -----------------
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:18644, timeout=2000,Attempt =1, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:18644, timeout=2000,Attempt =2, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:18644, timeout=2000,Attempt =3, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:28252, timeout=2000,Attempt =1, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:28252, timeout=2000,Attempt =2, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:28252, timeout=2000,Attempt =3, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:39493, timeout=2000,Attempt =1, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:39493, timeout=2000,Attempt =2, #bytes=144
>>> KDCCommunication: kdc=kdc.rabbit.hole UDP:39493, timeout=2000,Attempt =1, #bytes=214
STDERR:
java.lang.ArrayIndexOutOfBoundsException: 16
at BadKdc.test(BadKdc.java:103)
at BadKdc.go(BadKdc.java:65)
at BadKdc3.main(BadKdc3.java:39)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:613)
at com.sun.javatest.regtest.MainWrapper$MainThread.run(MainWrapper.java:94)
at java.lang.Thread.run(Thread.java:717)

JavaTest Message: Test threw exception: java.lang.ArrayIndexOutOfBoundsException: 16
JavaTest Message: shutting down test

STATUS:Failed.`main' threw exception: java.lang.ArrayIndexOutOfBoundsException: 16

TEST RESULT: Failed. Execution failed: `main' threw exception: java.lang.ArrayIndexOutOfBoundsException: 16
--------------------------------------------------
The BadKdc<n> tests are failing again. After hundreds of JPRT test, I see several different kinds of failures:

Once, A BindException;

Eleven times, timeout for k2. This always happens to the first UDP attempt to access k2 after it's turned on. Does not look like a timeout problem because I've tried timeout value of 5 seconds and the KDC side has no log on receiving the packet. The 2nd and 3rd packet to the same port are always processed in time. This happens on BadKdc3 (8 times), BadKdc1 (once), and BadKdc4 (twice), only on solaris-i586 or solaris-x64. The strange thing is, k3 is started earlier and it never sees any packet lost.

Update: Amy found failures on k3, so the last sentence in the previous paragraph is not "strange" now. She also reports a DER encoding error. It might be of the same reason as BindException: the KDC we want to open cannot be opened because another process is using the port. On the other hand, a KDC we do not want to start but its port might also be opened by another process, sending a packet to it will result in an response we cannot recognize.