[SATLUG] Rackspace

Brad Knowles brad at shub-internet.org
Tue Nov 10 22:02:28 CST 2015


On Nov 10, 2015, at 2:06 PM, typedeaf at yahoo.com wrote:

> In the end, I left Rackspace because there wasn't a path for where I wanted to go, and the pay was not very competitive given my skill set.
> As for your current job skills, let me give you some harsh reality. When you say, "I know subnetting, routing, and I have my Network+", that doesn't really say much. What you are describing is a Network Admins primary skill set, but I am going to guess that you have never logged into a Cisco device. If you want to be a network admin, learn Cisco. I must have conducted 100+ interviews at Racksapce. In fact, I wrote/compiled the interview questionnaires. Interviews at big IT companies are BRUTALLY harsh. Be prepared to be thoroughly questioning on anything your resume is stating you know. So, if you think you know networking, be prepared to get drilled on the topic. Do you understand VLANs? How does VLAN tagging work? Where is the tag? What layer is VLAN tagging? What is the default VLAN and how is it used? How can you apply ACLs to VLANs? How can you replicate VLANs across multiple switches? What about link aggregations and the various protocols for it? What about STP? When do you need it and what does it do? These are all questions that a CCNA (basically L1 Cisco admin) should be able to answer. So make sure you clarify your knowledge of networks and routing before the interview starts. Make sure you know what you don't know, and don't be afraid to admit it. You will sound far less ignorant by admitting it, than trying to make up an answer and faking it.

One of the things that killed me about the times I did actually have a phone interview with them, the person at the other end obviously didn’t know anything about the questions they were asking, and they were using a set from a public page.  They even gave me the URL to the page, so that I could read along.

And every single question on that page had major problems.  I don’t remember the details, but I do remember challenging the fundamental basis of the question that was incorrect, and then having that thrown back at me as “WRONG!” because it wasn’t the precise answer that was typed into the form that they were reading from.

If you’re going to ask me DNS questions because you see that I have DNS on my resume, that’s fine and dandy — just make sure that you ask good questions, or at least questions that are correctly formed, even if they are very simple.  Otherwise, as one of the Technical Reviewers of the book “DNS and BIND” by Albitz and Liu, I’m going to tear your questions apart.  And if you’re not ready for that, then you’ve got a problem.

Same with Sendmail — if you’re going to ask me e-mail/SMTP related questions, well you should be prepared for the fact that I was a technical reviewer for the book by Bryan Costales, and I’ve done a number of invited talks on the subject at various conferences like LISA.  There’s nothing quite like telling an entire room of people at LISA about how to scale sendmail system performance, while you’ve got Eric Allman sitting in the front row.


On the subject of doing an interview, on either side of the desk, I would say that the most important thing is to know when to say that you don’t know the answer but that you can look it up.  If someone quizzes me on arcane command-line parameters for a particular program, I may well tell them that I don’t know the specifics of that particular version of that particular program, because I’ve dealt with dozens of different versions of that program over the years — but I can look it up on the man page.  And if they can’t accept that answer, then odds are that’s not a place I want to work.

On the flip side, I know a bit about networking, but I’m certainly no CCNA, and if they were to start throwing those kind of questions at me then I would tell them that.  Again, if they can’t accept that answer, then that’s not a good place for me.


A few of years back, I interviewed for a position as a senior engineer at Bazaarvoice.  I was going to be working in a DevOps position for Ernest Mueller, who is a guy I consider a friend of mine from the Austin Cloud User Group.  Frankly, I thought that interview went pretty well.

But there was this one guy who kept asking me various questions about how to set up web servers, and I kept telling him that I’m a general performance tuning guy and I don’t know a great deal of specifics of doing performance tuning for web, but that I could learn.

I never did get that job.  And Ernest never told me the reasons why.  However, it wasn’t too long before Ernest left that company and went somewhere else.  So, maybe my honesty about “I’m not a web guy” cost me that job.  Or maybe Ernest saved me from disaster.


Don’t be afraid to say that you don’t know.  Be open about how you would go about finding out how to answer that question.

When I’m on the other end of the table, I don’t want anyone to try to “baffle me with bullshit”.  Skills and knowledge can be taught, but talent for problem solving and learning can’t.

In those circumstances, I want to push you to the limits of your knowledge, so that you can give me an indication as to how you would go about finding the answer to a problem.

> That being said, every 'admin' , wether DBA or SA or MW admin, should know at least basic LAN networking. I can't tell you how many times I have seen people hit a brick wall and throw their hands in the air at some issue, just to find out that they do not have a reasonable default gateway set.

Or they don’t have proper nameservers set up.  Or they don’t understand about path MTU discovery.  Or they don’t understand how the TCP three-way handshake works.

And so many more.

> Networking at Rackapce was and probably still is its own island. They have traditional networking admin that work on LAN issues, and they have 'Network Security' roles that focus on 'security' devices --primarily firewalls, but also load balancers and other devices that are not straight up switches and routers. The Cisco people did not know Linux, and the Linux people did not know Cisco.

That’s been my experience at virtually every place I’ve ever worked.  Most networking guys also don’t really understand how certain network services work, if they don’t run on routers or switches.  So, they don’t really understand DNS.  Or NTP.  They might (or might not) understand about DHCP or RADIUS.

And virtually no host administrators I’ve known understand the first thing about networking, or network services like DNS, NTP, DHCP, or RADIUS.

Which leaves a nice little hole in the middle that I made a career out of specializing in.

Well, at least until I got into this DevOps thing, because so many places had decided overnight they could cut their staff in half by replacing all their “admins” with “DevOps” guys and make the people involved do twice as much work.

--
Brad Knowles <brad at shub-internet.org>
LinkedIn Profile: <http://tinyurl.com/y8kpxu>

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