The CCNA will teach you many of the basic skills you will need.
IP subnetting, this is essential, and also the basic IOS commands, which you will use daily. If you are studying through the Cisco Academy Program then you also learn to use diagnostic tools such as Wireshark, and also some debugging and configuration practice. Basic knowledge of routing protocols is also covered (RIP, OSPF and EIGRP). All this is useful when you are interviewed.
If you pass the CCNA exam, you will have a lot of the elementary knowledge to start in a network administrator role. Try to add more knowledge of the IOS commands, and what they do in a ‘real’ environment, why they are used, and what the different options do that allow you to tailor the command to work in a particular environment.
Above all, show enthusiasm for the subject, and a willingness to learn more.
When I was recruiting, those were some of the things I was looking for in a junior engineer.