Doubts regarding Keytab file

[Abhishek Kaushik]

Hello,

I am trying to understand how Kerberos works and so came across this file
called Keytab which, I believe, is used for authentication to the KDC
server.

Just like every user and service(say Hadoop) in a kerberos realm has a
service principal, does every user and service have a keytab file?

Also, does authentication using keytab work on symmetric key cryptography
or public-private key?