He’s a blind lawyer by day, a superhero by night — and an engineering feat to boot.

This past Thursday, Netflix invited a select group of journalists from around the world to its offices in Los Gatos, California for the launch of season 2 of “Daredevil.” The company used the day to promote the show, and had lead actor Charlie Cox as well as “Daredevil” showrunners Doug Petrie and Marco Ramirez on hand to talk about the evolution of the unlikely hero.

But Netflix also gave the assembled press a rare look behind the curtain, revealing what it takes to distribute TV shows to global audiences. Speakers touched on content distribution technologies, recommendation engines, streaming devices and more, and even gave journalists an inside look at the war room where engineers monitored the global launch of the show at midnight.

Throughout the day, speakers revealed a number of interesting tidbits on how Netflix brings “Daredevil” to viewers around the world. Here are five of them:

Netflix lets you pick the ‘Daredevil’ cover art

The folks at Netflix prepared for weeks for the launch of the new “Daredevil” season — but they hadn’t actually picked the cover art to promote the show on the service’s website and within its apps when it went live at midnight.

Netflix subscribers will get to see one of these eight “Daredevil” covers as part of a test.

Image: Janko Roettgers / Variety

That’s not for a lack of oversight: Netflix’s VP of product innovation Todd Yellin explained that his team is continuously testing images to figure out which one is the most appealing to customers. The company’s designers had prepared not one but eight different images for the new season of “Daredevil,” and are now showing each of them to randomly selected customers. In the end, the company will pick the best-performing title and use it for everyone. “We’ll see what wins,” Yellin said.

SEE MORE: This Simple Trick Helped Netflix Increase Video Viewing by More Than 20 Percent

Netflix has been doing this for some time for its shows, with at times surprising results. For “Fuller House,” Netflix tested six different images. Most of them featured some or all of the show’s key actors, but one only depicted the show’s logo and San Francisco’s iconic Golden Gate bridge. In the end, the bridge won, resulting in five percent more plays.

Netflix tested six cover images for “Fuller House” — with unexpected results.

Image: Janko Roettgers / Variety

“Daredevil” won’t kill the internet

“Daredevil” may be a hugely popular show, but Netflix doesn’t actually expect its subscribers to use up a lot more bandwidth than they would during any other week. “Those subscribers may have been watching something on Netflix anyway,” said the company’s VP of content delivery, Ken Florance.

Views of “Daredevil” season 2 spiking after it launched at midnight.

Image: Janko Roettgers / Variety

Still, traffic and reliability are major considerations for Netflix. The company now has more than 75 million users around the world who consume more than 125 million hours of content every day. That’s why Netflix has built its own content delivery network, dubbed OpenConnect, which now consists of thousands of servers located directly within big internet exchanges as well as facilities from many of the world’s biggest internet service providers.

SEE MORE: Netflix Bandwidth Usage Climbs to Nearly 37% of Internet Traffic at Peak Hours

OpenConnect servers cache copies of “Daredevil” and other shows and movies locally, and they’re especially important as Netflix expands around the globe. When the company launched in Brazil in 2011, it was still delivering every single stream straight from data centers in Dallas and Miami. These days, 85 percent of all Netflix streams in Brazil are coming from local content caches — and Netflix only has to send the files for the show once to these caches to allow everyone to binge.

It only took 15 minutes to get ‘Daredevil’ everywhere

One of the challenges with these caches is that they constantly need to be kept up to date. Netflix keeps copies of its entire local catalog in caching servers located at central internet exchanges, and then sends a subset to servers that are much closer to its subscribers — say, within the data center of a local internet service provider.

For that, Netflix uses predictive algorithms to anticipate which content will be watched in which region. “We calculate the future popularity,” explained Florance — and it’s not a one-size-fits-all approach. “We have to do different popularity calculation for different countries and different regions.”

A look inside the Netflix war room, where developers monitored the launch of “Daredevil” season 2.

Image: Janko Roettgers / Variety

Florance said Thursday that it used to take Netflix many hours to distribute a show to all of its caching servers around the world. For “Daredevil,” it was able to send copies to all of its major caches within 15 minutes. That’s a feat that will be especially important as Netflix launches its new Chelsea Handler talk show on May 11th. The show will be taped every Wednesday, Thursday and Friday, and reach subscribers about twelve hours later.

Netflix’s disks will soon stop spinning

Netflix custom-builds its OpenConnect servers for the task at hand, and makes sure that they meet the specifications of internet providers for hardware housed in their facilities. Each OpenConnect device is chock-full with hard drives, holding thousands of video files. And when one drive fails, storage just gets reallocated to make the most of it before the entire unit eventually has to be serviced.

One of Netflix’s custom-made OpenConnect servers. each features a different movie quote, which are submitted by employees.

Image: Janko Roettgers / Variety

Netflix now tries to cut down on those service calls by gradually replacing traditional hard drives with flash-based storage, which is essentially the same kind of storage being used in iPads, digital cameras and increasingly also consumer laptops. Flash drives have no moving parts, which makes them a lot faster — an important feature as Netflix tries to cut down on every millisecond of video buffering.

They’re also known to consume a lot less power, and are increasingly more reliable than traditional hard drives. Netflix is already using Flash drives to serve between 70 and 80 percent of the content from OpenConnect servers located at big internet exchanges. In the next three to four years, it aims to replace all of its spinning hard drives with flash, according to Florance.

Netflix tests until the very last second

Netflix is known to be obsessive about testing, constantly trying out new ideas with a subsets of its users. In the case of “Daredevil,” the company didn’t just test the cover art used to promote the show. It also showed a countdown timer to a percentage of its users worldwide, constantly measuring if those users were more likely to stay tuned and actually stream the first episode of the show at midnight. If successful, Netflix may bring the counter back for other show premieres.

The Daredevil countdown timer, as displayed in the launch war room.

Image: Janko Roettgers / Variety

Yellin explained Thursday that Netflix doesn’t test these things in a vacuum. The company routinely goes to visit new and existing users to learn about their media consumption patterns, and the way they use Netflix. Based on this research, employees develop hypotheses about product improvements that are then tested with thousands or tens of thousands of users.

Some of these tests are about smaller improvements. But more often, tests are measured against very fundamental metrics: Are users more likely to stay engaged, and maybe extend their free trial to become paying subscribers, or are they going to cancel their service? In other words: Are they going to add to the growth of the company? Said Yellin: “We are not out to make cool bells and whistles for power users.”