

System Administrator Interview Cheat Sheet - r11t
http://mj12net.org/index.php/system-administrator-interview-cheat-sheet.html

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nailer
This is really out of date.

* nslookup has been deprecated by its makers for years now.

* ip route's replaced 'route', which still works but won't show you all the things that ip route can.

* Nothing on dot1q VLAN tagging, which is pretty common these days

* No CDP from hosts, which is also pretty common

* No Postfix or any other non-Sendmail mailer.

* The somewhat bizarre 'bash script to validate RPM files'. Why not just teach the proper query syntax or, for scripting, RPM & yum APIs?

* Solaris.

If you're being asked these questions, or your interviewer is expecting these
answers, you may wish to consider whether you want the role.

~~~
brianb0
I agree it is out of date. I haven't worked on that page for over a year I
think. I have done so much cool stuff in the industry since then and I keep
meaning to document it and share what I've learned but I've just been lazy. I
did however document how to do 801q packet tagging in there. I did a lot of
that about a year ago at NetApp where I worked with a lot of VLANs and virtual
machines.

~~~
dstorrs
Outdated or not, it's an impressive list.

You might expand the packaging section to include at least apt-get, and the
source control section to include at least svn and preferably git. There's
really no reason to still be using CVS at this point.

~~~
ludwig
Don't forget darcs. I find it useful since they distribute statically linked
executables. Installation then becomes a matter of just dropping darcs into a
bin directory.

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jrg
(Cheat sheet? Cheat Novella, more like! I think it's probably past the point
where it needs to be split up a bit, even if only for your own benefit.)

"How do you check disk usage. How do you trouble shoot a high disk usage
issue"

which is fine, until someone's done something similar to the next bit of
advice - i.e. deleted some "old", large files that were still open by the
application.

Better: compare filesystem usage (with df), against disk space used (with du),
to deduce that there's an open file that has been unlinked. Then use lsof
(whatever Sun say about pfiles or about dtrace, lsof is an essential tool) to
look for processes with open files that have large offsets.

And, when deleting large files, check whether they're open, and truncate them
before deleting them if you're not sure.

(note to another poster - ain't nothing wrong with Solaris! But I'm not really
sure what interviewer might ask questions about the OSI 7 layer model, these
days, and I agree that there's a real odd jumble of scripting snippets in
there: best advice to anyone wanting to improve that side of their systems
administration skills, is to read a copy of Unix Power tools.)

~~~
nailer
Systemtap has an open files tap which has similar advantages over lsof FYI.

~~~
brianb0
Systemtap looks very cool. I am reading about it now. I will try it ou on my
FC11 VM.

~~~
nailer
Re: pfiles equivalent (now I'm not on the phone and can chase it up)

<http://kbase.redhat.com/faq/docs/DOC-9942>

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Scott_MacGregor
Thank you, this is very well laid out and easy to use.

~~~
brianb0
Thanks for the compliment.

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spudlyo
Much of this content is lifted from other sites and articles, without
attribution, with little or no value added commentary or presentation. I'm not
sure why I'm offended by this, but I am.

~~~
brianb0
Much of it was, I created this in my spare time to help me pass interviews. I
was being interviewed by people with less time than me in the industry who
didn't know what they were talking about and they were reading from a script
or just seeing if I knew as much about their own personalized environment as
they did. I needed a one stop place to dump a bunch of stuff I'd need to be
able to answer questions.

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dnsworks
This seems to be geared towards the type of systems administrator that you're
not really looking to hire, if you're the kind of startup that hangs out on
hacker news.

Frankly, the Solaris & NIS+ questions are useless. You will not use either in
a modern web startup, unless you're doing something wrong. Ditto for the AIX
questions, LPARS, HP-UX, and Power-VM sections.

Ask a sysadmin questions relevant to your environment, or where you want your
environment to go. Don't expect them to be a domain expert in every single
region, and don't give weight to domain expertise irrelevant to your startup.
I coached a friend through a phone interview with a generic LAMP-based startup
recently whose hiring consultant spent an hour asking him questions about BGP,
OSPF, Solaris, VMWare and EMC specific SAN devices.

The interviewer was a typical big company/academic systems administrator who
had no startup experience. It was pretty ridiculous, these questions were
asked by the interviewer because that's what his expertise was in, not because
any of these were ever going to have any relevancy for this startup.

He passed, of course, and now their whole environment are AMIs.

I will say that I think any systems administrator today who isn't excited
about learning Puppet or Chef is the wrong choice for a web startup.

~~~
bestes
This is the first I have heard of either Chef or Puppet. They both look
interesting, but I can't tell how mature they are. Anyone care to expand?

~~~
dnsworks
Puppet and Chef are both Ruby based configuration management systems. One
might say that CFEngine begat Puppet which begat Chef.

Puppet was written by Luke Kanies after years of frustration as a systems
administrator working with CFEngine. It's roughly three years old. It's
mailing list has over 2,000 subscribers, and when I attended the recent
PuppetCamp there were roughly 200 active participants in attendance. My very
anecdotal estimate is that there are at least 30,000+ nodes using Puppet (My
old consulting company was responsible for 6,500 nodes). Puppet is now
maintained by Luke's startup, <http://reductivelabs.com/> which took a $2m
Series A round from True Ventures this summer. Puppet is written in
Ruby/Rails, and implements it's own DSL for describing the configuration of
your systems and applications.

Chef was written by Adam Jacobs of HJK Solutions, now <http://opscode.com/>.
Adam was a vocal Puppet consultant, and wrote Chef in response to
dissatisfaction around the handling of Puppet Bug #1010
(<http://projects.reductivelabs.com/issues/1010>), related to problems with
idempotency initiated from Puppet's directed graph. Chef is maintained by
Opsocde, whose CEO is Jesse Robbins from Oreilly and whose CTO is Adam Jacobs,
they received a Series A round of $2.5m from Draper Fisher this summer.

Both are open-source, and sit somewhat in the same genre as CFengine, ISconfv4
(mostly abandonware), and BCFG2.

