Why is JDK1.8.0u121 unable to find the kerberos default_tkt_enctypes types? (KrbException: no supported default etypes for default_tkt_enctypes)

I've seen this before. Try this. Copy the keytab into the C:\Program Files\Java\jdk1.8.0_121\bin directory and try again with the simpler command shown below from within that directory. You don't need to append the Kerberos realm to the SPN since you have the realm defined already in krb5.conf, so I removed it.

kinit -k -t tomcat_ad.keytab HTTP/dev26.devdevelopment.com

If it still doesn't work, be sure you really do have the unlimited strength JCE jar files inside the \lib\security directory. Although you said you did, a Java JRE upgrade can overwrite them.

EDIT: On the Account tab of the AD user account devtcadmin, ensure the box "This account supports Kerberos AES 256 bit encryption" is checked.

If it still doesn't work, then on the Windows 7 machine, in C:\Windows\krb5.conf, comment out the four below lines as shown. They are not required, as Kerberos is going to use the highest possible encrytpion types anyway, and in Windows 7/2008 and above, TCP is used by default so you do not need to set the UDP preference limit.

#default_tkt_enctypes=aes256-cts-hmac-shal-96
#default_tgs_enctypes=aes256-cts-hmac-shal-96
#permitted_enctypes=aes256-cts-hmac-shal-96
#udp_preference_limit=1

Take a quick glance at my TechNet article for further reference on this: Kerberos Keytabs – Explained