It's a good question. You would do well to read up on how DNSBLs and DNS work. If a DNSBL's authoritative server goes down there's no risk of false positives. You don't get a positive response for random IPs when the list is not answering. And if you look up the IP of someone who's actually sending spam and you don't get a positive result, that's okay too. The list shouldn't be your only check for whether something is spam. And if you look up an IP and the server doesn't give any response, that's okay too. Your mail system shouldn't freak out and mark the email as spam or otherwise fail to handle the email.

You feel dirty for using the Spamhaus blacklists? Which ones do you use? Do you know how they're generated?

I don't use the SBL, though I'm philosophically not that far from approving of it.

I don't use the PBL, I just disagree with the idea behind it.

I don't use ZEN, obviously, being an aggregate including lists I don't agree with.

I do use XBL. To me it just makes sense. And I don't have one whit of regret about it.

The different lists published by Spamhaus distinguish whether the IPs are directly responsible or are organizationally related. There is no abuse of power here — customers subscribe to the lists that they want, and use those lists to block as they see fit. Spamhaus isn't forcing anyone to use the lists, nor is it misrepresenting what's in the lists.

I think the idea is that acting as you imagine you would behave correlates more highly with how you actually would behave than randomness does. Take the data as a correlation, be cognizant of the possible degrees of accuracy, and extrapolate from there. You maybe get broad strokes showing you the directions things could go in an actual situation, but that's not nothin'.

Actually, moving sshd to a different port is for added security.

It'll be some time before automated scans and worms try to find SSH on something other than port 22 in any substantial frequency. So moving the port gets you a reduction in attack frequency. That's of value. It's additional security.

Requiring a remote system to send SYN packets to 16111 28123 and 22222 before opening port 22 to them is just another way to reduce frequency (albeit using a much higher hurdle). The difference is degree, not kind, so it's not that one of these actions is actual security and the other isn't.

The point behind having 4 different solutions was to be flexible in my thinking, ready for whatever a scenario might call for. The question, being a test question without a genuine context, leaves open the range of possibilities, using only a hint (in place) to constrain the solution. There are situations that could use the two algorithms you find unsuitable (unsuitable presumably for the situations you commonly experience and thus judge things by).

This is fun. Okay, I'm not a JavaScript programmer, but here are my submissions (the first two solutions taking 2-3 minutes to create):

First we create the array.

    var ary = [1,2,3,4,5];

Now... First reversal method, assuming static array size and these particular numbers:

    ary = [5,4,3,2,1];

Whether this is "in place" depends on how JavaScript works. Seems likely to me that it'll do it in place.

Second method, assuming static array size, this particular array size, and using any (numeric!) values within the array:

    for (i = 0; i < 2; i++)
    {
        t = ary[i];
        ary[i] = ary[5-i-1];
        ary[5-i-1] = t;
    }

Obviously uses a temporary variable. Depending on what was meant, that may violate the "in place".

Okay, after a couple more minutes, here's another:

    for (i = 0; i < 2; i++)
    {
        ary[i] += ary[5-i-1];
        ary[5-i-1] = ary[i] - ary[5-i-1];
        ary[i] -= ary[5-i-1];
    }

Again, assuming a 5 element array. No memory aside from the array used, though more (simple arithmetic) operations used.

Oh, shit, hey... Does this work?

    for (i = 0; i < 2; i++)
    {
        ary[i] ^= ary[5-i-1];
        ary[5-i-1] ^= ary[i];
        ary[i] ^= ary[5-i-1];
    }

Seems to. I'm not that knowledgeable, so I don't know this, but I get the sense that binary manipulations may be faster than arithmetic.

Also, I expect things like the 5-i-1 to get evaluated once and for the compiler to not bother calculating it again. If this were a concern, then storing the result in a temporary variable might make sense, depending on the overhead (and whether this again violates "in place").

Critiques, please?

More seriously, who's to say the writers of this algorithm can't run it in reverse to frame someone?

Oh, clever.

But now future courts can point to your post to show that the idea was common or at least public knowledge, empowering stylometric identification deniability in cases of plausible framing.

The Syrian civil war is one of the main topics. The other, arguably primary main topic is Apple's censorship. The sub-topic being discussed under Apple's censorship was platforms and social pressure. The sub-topic underneath that was Internet Explorer as an example of such. To think of IE and the civil war as a dichotomy is a mistake, though I certainly also feel the emotional impact of contrasting the two.

I do choose to be how I am, and I do catch flak for being different. That flak is social pressure.

Maybe you don't remember the days before Open Office, receiving important documents you couldn't read or needing to create important documents that you couldn't make without Microsoft software. Maybe you don't remember how many websites were IE-specific, or how it was business suicide to build a site without catering to the IE userbase. Do you think that those pressures weren't real?

You don't really care what people think, any more than I do.

You probably care less. It sounds like you don't have to interact in a business environment and maybe you don't have many friends who want to be in touch via Facebook- Oh, but you do use Facebook. Do you also build websites? When did you start web surfing? IE was a thorn in the sides of everyone who wanted a better browser, but folks had little choice except to deal with it -- that's social pressure. You don't have to worry about IE or Office now. It sounds like you didn't experience these things. And the one example of extant pressure, Facebook, you are using. So maybe it's hard for you to understand. Look around, though. There are plenty of other normative things that society smooths the way for, and which swimming against is damned hard.

Don't let your disdain for haughtiness distract you when you think you've caught whiff of it. There's a real issue here.

Even almost completely spelled out it's hard to get.

If each bandit takes a single bean from each villager, they will have only done 1% harm, and so they'll feel morally comfortable. But there are 100 bandits, which means each villager still loses their entire 100 bean meal.

That's the point. Even if you do only a little harm to others in your quest for self-satisfaction, it still adds up to others suffering substantially.

Did anyone else miss this?

Were you around for most of this curve? Did you find that time pleasant?

That's reassuring. I'll have to look at the issue in more depth.

The primacy of apps over web is something to consider. That is, apps are more prominent and more capable.

Okay, granted, it depends on context.

Within the realm of Apple systems that run only apps we have "favoring complete obedience or subjection to authority as opposed to individual freedom" and "the act or practice of supervising the manners or morality of others".

Part of the problem is that opt-in commercial systems become de facto social requirements. Internet Explorer, Office, Facebook, LinkedIn, smartphones... It's hard to navigate society without opting in. I use none of these things, and having opted out puts pressure on me. People around me think I'm weird (because I am strange, I am unusual and hard to understand) and they feel judged by my refusing to do what they do (this is similar to how just being a vegetarian is threatening to others) and that puts strain on my relations.

So I'm a component of a larger organism, society. What society chooses, whether enforced intentionally, using written rules and men with guns, or enforced incidentally, by the fact of social pressure, is what I am subject to. If society ignorantly opts to relinquish freedom by adopting some corporation's politically- and morally-constrained walled garden, they apply that authoritarianism and censorship to me as well.

I'm still pissed off about Internet Explorer.

You reject the quality and/or political message of the app, but miss the issue that Apple alone gets to say what's appropriate. Apple's authoritarian censorship is a "political game".