I am 26 and I have worked at a software consultancy company for four years. My time is mixed 50% between doing development, and I guess simple sysadmin tasks. Tasks would include things like: setting up Apache, MySQL, changes to DNS zone configuration, babysitting 200 devices with Nagios, updating Debian/BSD systems, running backups and so on. I could do firefighting as a full time job there.
Out of the development work (mostly python) and sysadmin work, I prefer the sysadmin work because the requirements are more easily defined. I think I like stitching together external software and playing with hardware more than developing software. At where I work, new software doesn't have specifications (due to ineptitude) and the rest of the work is endless tweaks to business logic.
So, on the basis of what I've seen, I think I'd like to err towards the sysadmin side and eventually get a full time job at it. I enthusiastically read "Practice of System and Network Administration" and it seems like fun. However, my lovely female manager doesn't want me doing anything but software development.
I feel that before I apply for a full time sysadmin job, becoming more rounded (i.e. learning more of the linux sysadmin space) is a good idea. For example, I was planning to expand my knowledge of mail systems (which is about limited to configuring postfix) and LDAP. I know little about networking (other than CIDR, subnet masks and so on), so I was considering learning the CCNA material and possibly taking the exam.
Is this idea of becoming more rounded generally a good idea? Does anyone have opinions on which topics to learn or how to learn them?