Hi
Answer to Q1 :
Best plase to compare the Catos and IOS is
www.cisco.com/go/fn
there you can search by ios names or platforms or features and compare images.
Answer to Q2 :
Yes you need Cryptographic version
Answer to Q3 :
K9 stand for Cryptographic version if you have ipservicesk9 you can do SSH in the feature navigator if you search the ios without K9 you will find this :
IP SERVICES W/O Crypto
that means this catos does not support Cryptographic.
Best Regards Bahman Mozaffari.
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