Since I started my career in networking, I have a doubt about the OSI and TCP/IP Model. Among the two models which one is in use presently? I guess its TCP/IP but don't know why. Can anyone help to explain? Thank you
ISO/OSI was competition for TCP/IP when networks were first being developed and standardized. TCP/IP won that battle, but the OSI reference model lived on as a way to understand "communication systems". Marinl is right though learn both and understand how they relate to each other. Don't worry to much about the ISO protocols such as x.25, clnp ... As you can imagine most are not relevant anymore, well except for is-is.