Tech Manifesto

Microsoft, as well as other respectable businesses ask questions in an interview that make you think “outside the box.” Listed are examples of abstract questions expected from certain high paying tech field jobs.

SDE/T position at Microsoft (Software Design Engineer in Test) Questions

• How would you deal with changes being made a week or so before the ship date?

• How would you deal with a bug that no one wants to fix? Both the SDE and his lead have said they won’t fix it.

• Write a function that counts the number of primes in the range [1-N]. Write the test cases for this function.

• Given a MAKEFILE (yeah a makefile), design the data structure that a parser would create and then write code that iterates over that data structure executing commands if needed.

• Write a function that inserts an integer into a linked list in ascending order. Write the test cases for this function.

• Test the save dialog in Notepad. (This was the question I enjoyed the most).

• Write the InStr function. Write the test cases for this function.

• Write a function that will return the number of days in a month (no using System.DateTime).

• You have 3 jars. Each jar has a label on it: white, black, or white & black. You have 3 sets of marbles: white, black, and white & black. One set is stored in one jar. The labels on the jars are guaranteed to be incorrect (i.e. white will not contain white). Which jar would you choose from to give you the best chances of identifying the which set of marbles in is in which jar.

• Why do you want to work for Microsoft.

• Write the test cases for a vending machine.

Microsoft Intern Questions

• Explain a database to a young child.

• Explain the Internet to your grandparents.

• What is your favorite web site? Why? Now improve it.

• Steve Jobs calls and asks you to improve the iPod. Go. (No bonus points for saying, Add WMA support!)

• You are in a boat with a rock, on a fresh-water lake. You throw the rock into the lake. With respect to the land, what happens to the level of the water in the lake goes up, goes down, stays the same?

Shawn Morrissey - Microsoft Employee

What Great .NET Developers Ought To Know

Everyone who writes code

• Describe the difference between a Thread and a Process?

• What is a Windows Service and how does its lifecycle differ from a “standard” EXE?

• What is the maximum amount of memory any single process on Windows can address? Is this different than the maximum virtual memory for the system? How would this affect a system design?

• What is the difference between an EXE and a DLL?

• What is strong-typing versus weak-typing? Which is preferred? Why?

• Corillian’s product is a “Component Container.” Name at least 3 component containers that ship now with the Windows Server Family.

• What is a PID? How is it useful when troubleshooting a system?

• How many processes can listen on a single TCP/IP port?

• What is the GAC? What problem does it solve?

Mid-Level .NET Developer

• Describe the difference between Interface-oriented, Object-oriented and Aspect-oriented programming.

• Describe what an Interface is and how it’s different from a Class.

• What is Reflection?

• What is the difference between XML Web Services using ASMX and .NET Remoting using SOAP?

• Are the type system represented by XmlSchema and the CLS isomorphic?

• Conceptually, what is the difference between early-binding and late-binding?

• Is using Assembly.Load a static reference or dynamic reference?

• When would using Assembly.LoadFrom or Assembly.LoadFile be appropriate?

• What is an Asssembly Qualified Name? Is it a filename? How is it different?

• Is this valid? Assembly.Load(”foo.dll”);

• How is a strongly-named assembly different from one that isn’t strongly-named?

• Can DateTimes be null?

• What is the JIT? What is NGEN? What are limitations and benefits of each?

• How does the generational garbage collector in the .NET CLR manage object lifetime? What is non-deterministic finalization?

• What is the difference between Finalize() and Dispose()?

• How is the using() pattern useful? What is IDisposable? How does it support deterministic finalization?

• What does this useful command line do? tasklist /m “mscor*”

• What is the difference between in-proc and out-of-proc?

• What technology enables out-of-proc communication in .NET?

• When you’re running a component within ASP.NET, what process is it running within on Windows XP? Windows 2000? Windows 2003?

Senior Developers and Architects

• What’s wrong with a line like this? DateTime.Parse(myString);

• What are PDBs? Where must they be located for debugging to work?

• What is cyclomatic complexity and why is it important?

• Write a standard lock() plus “double check” to create a critical section around a variable access.

• What is FullTrust? Do GAC’ed assemblies have FullTrust?

• What benefit does your code receive if you decorate it with attributes demanding specific Security permissions?

• What does this do? gacutil /l | find /i “Corillian”

• What does this do? sn -t foo.dll

• What ports must be open for DCOM over a firewall? What is the purpose of Port 135?

• Contrast OOP and SOA. What are tenets of each?

• How does the XmlSerializer work? What ACL permissions does a process using it require?

• Why is catch(Exception) almost always a bad idea?

• What is the difference between Debug.Write and Trace.Write? When should each be used?

• What is the difference between a Debug and Release build? Is there a significant speed difference? Why or why not?

• Does JITting occur per-assembly or per-method? How does this affect the working set?

• Contrast the use of an abstract base class against an interface?

• What is the difference between a.Equals(b) and a == b?

• In the context of a comparison, what is object identity versus object equivalence?

• How would one do a deep copy in .NET?

• Explain current thinking around IClonable.

• What is boxing?

• WIs string a value type or a reference type?

• What is the significance of the “PropertySpecified” pattern used by the XmlSerializer? What problem does it attempt to solve?

• Why are out parameters a bad idea in .NET? Are they?

• Can attributes be placed on specific parameters to a method? Why is this useful?

C# Component Developers

• Juxtapose the use of override with new. What is shadowing?

• Explain the use of virtual, sealed, override, and abstract.

• Explain the importance and use of each component of this string: Foo.Bar, Version=2.0.205.0, Culture=neutral, PublicKeyToken=593777ae2d274679d

• Explain the differences between public, protected, private and internal.

• What benefit do you get from using a Primary Interop Assembly (PIA)?

• By what mechanism does NUnit know what methods to test?

• What is the difference between: catch(Exception e){throw e;} and catch(Exception e){throw;}

• What is the difference between typeof(foo) and myFoo.GetType()?

• Explain what’s happening in the first constructor: public class c{ public c(string a) : this() {;}; public c() {;} } How is this construct useful?

• What is this? Can this be used within a static method?

ASP.NET (UI) Developers

• Describe how a browser-based Form POST becomes a Server-Side event like Button1_OnClick.

• What is a PostBack?

• What is ViewState? How is it encoded? Is it encrypted? Who uses ViewState?

• What is the element and what two ASP.NET technologies is it used for?

• What three Session State providers are available in ASP.NET 1.1? What are the pros and cons of each?

• What is Web Gardening? How would using it affect a design?

• Given one ASP.NET application, how many application objects does it have on a single proc box? A dual? A dual with Web Gardening enabled? How would this affect a design?

• Are threads reused in ASP.NET between requests? Does every HttpRequest get its own thread? Should you use Thread Local storage with ASP.NET?

• Is the [ThreadStatic] attribute useful in ASP.NET? Are there side effects? Good or bad?

• Give an example of how using an HttpHandler could simplify an existing design that serves Check Images from an .aspx page.

• What kinds of events can an HttpModule subscribe to? What influence can they have on an implementation? What can be done without recompiling the ASP.NET Application?

• Describe ways to present an arbitrary endpoint (URL) and route requests to that endpoint to ASP.NET.

• Explain how cookies work. Give an example of Cookie abuse.

• Explain the importance of HttpRequest.ValidateInput()?

• What kind of data is passed via HTTP Headers?

• Juxtapose the HTTP verbs GET and POST. What is HEAD?

• Name and describe at least a half dozen HTTP Status Codes and what they express to the requesting client.

• How does if-not-modified-since work? How can it be programmatically implemented with ASP.NET?

• Explain < @OutputCache%> and the usage of VaryByParam, VaryByHeader.

• How does VaryByCustom work?

• How would one implement ASP.NET HTML output caching, caching outgoing versions of pages generated via all values of q= except where q=5 (as in http://localhost/page.aspx?q=5)?

Developers using XML

• What is the purpose of XML Namespaces?

• When is the DOM appropriate for use? When is it not? Are there size limitations?

• What is the WS-I Basic Profile and why is it important?

• Write a small XML document that uses a default namespace and a qualified (prefixed) namespace. Include elements from both namespace.

• What is the one fundamental difference between Elements and Attributes?

• What is the difference between Well-Formed XML and Valid XML?

• How would you validate XML using .NET?

• Why is this almost always a bad idea? When is it a good idea? myXmlDocument.SelectNodes(”//mynode”);

• Describe the difference between pull-style parsers (XmlReader) and eventing-readers (Sax)

• What is the difference between XPathDocument and XmlDocument? Describe situations where one should be used over the other.

• What is the difference between an XML “Fragment” and an XML “Document.”

• What does it meant to say “the canonical” form of XML?

• Why is the XML InfoSet specification different from the Xml DOM? What does the InfoSet attempt to solve?

• Contrast DTDs versus XSDs. What are their similarities and differences? Which is preferred and why?

• Does System.Xml support DTDs? How?

• Can any XML Schema be represented as an object graph? Vice versa?

Thanks to Scott Hanselman.

If Richard Feynman applied for a job at Microsoft

Interviewer: Now comes the part of the interview where we ask a question to test your creative thinking ability. Don’t think too hard about it, just apply everyday common sense, and describe your reasoning process.

Here’s the question: Why are manhole covers round?

Feynman: They’re not. Some manhole covers are square. It’s true that there are SOME round ones, but I’ve seen square ones, and rectangular ones.

Interviewer: But just considering the round ones, why are they round?

Feynman: If we are just considering the round ones, then they are round by definition. That statement is a tautology.

Interviewer: I mean, why are there round ones at all? Is there some particular value to having round ones?

Feynman: Yes. Round covers are used when the hole they are covering up is also round. It’s simplest to cover a round hole with a round cover.

Interviewer: Can you think of a property of round covers that gives them an advantage over square ones?

Feynman: We have to look at what is under the cover to answer that question. The hole below the cover is round because a cylinder is the strongest shape against the compression of the earth around it. Also, the term “manhole” implies a passage big enough for a man, and a human being climbing down a ladder is roughly circular in cross-section. So a cylindrical pipe is the natural shape for manholes. The covers are simply the shape needed to cover up a cylinder.

Interviewer: Do you believe there is a safety issue? I mean, couldn’t square covers fall into the hole and hurt someone?

Feynman: Not likely. Square covers are sometimes used on prefabricated vaults where the access passage is also square. The cover is larger than the passage, and sits on a ledge that supports it along the entire perimeter. The covers are usually made of solid metal and are very heavy. Let’s assume a two-foot square opening and a ledge width of 1-1/2 inches. In order to get it to fall in, you would have to lift one side of the cover, then rotate it 30 degrees so that the cover would clear the ledge, and then tilt the cover up nearly 45 degrees from horizontal before the center of gravity would shift enough for it to fall in. Yes, it’s possible, but very unlikely. The people authorized to open manhole covers could easily be trained to do it safely. Applying common engineering sense, the shape of a manhole cover is entirely determined by the shape of the opening it is intended to cover.

Interviewer (troubled) : Excuse me a moment; I have to discuss something with my management team. (Leaves room.)

(Interviewer returns after 10 minutes)

Interviewer: We are going to recommend you for immediate hiring into the marketing department.

Thanks to Keith Michaels.

How Would You Move Mount Fuji?

If you’re interested in a book about the high-tech interview process, including lots of info about MS specifically (and some material from yours truly), check out How Would You Move Mount Fuji? by William Poundstone.