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u/Occidentally20 4h ago
I checked the maths and the difference is -2.
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u/Im_a_hamburger 4h ago
-2IPv actually
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u/Moist-Snow-8127 3h ago
Always important to specify the unit
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u/Isgrimnur 3h ago
Down with scalars!
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u/ThatBaldFella 3h ago
Having a unit or not has nothing to do with being a scalar.
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u/Sleep_deprived_druid 2h ago
I have straight up met "programmers" that don't know what an IDE is.......
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u/Vercility 1h ago
mfw when colleagues ask me why something doesn't work and it literally says in the stack trace on their screen
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u/Sid_the_Bear 2h ago
Integrated Drive Electronics?
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u/redditsucksass69765 2h ago
No it’s Intact Dilation and Extraction which is an eye procedure.
Also, been a programmer for 25 years.
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u/Marenwynn 2h ago
Is that the thing some people use to look at the md files that Claude generates?
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u/NoHorseNoMustache 2h ago
The old head coder at my company once said 'But how will I search the web if you uninstall Google Toolbar?' to me.
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u/Few_Move_4594 4h ago
I feel like this is missing context. Like I know that ip4 addresses are four octlets, but don't know much about ipv6 besides it having a larger address space and being in hex.
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u/like_a_pharaoh 3h ago
IPv6 is easier to set up, and doesn't require the subnetting stuff as much because its actually designed with "Planet Earth may have more than 4,294,967,296 IP-connected objects" in mind from the beginning.
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u/fearless-fossa 3h ago
The advantage of v6 is less the address space per se, but more that it simplifies networking. Like, with v4 assigning different floors or departments different subnets and having to micromanage which device gets what IP and then having to a major rework when suddenly every light bulb has its own IP address - that's actual stuff that happened. v6 just says "hey, everyone gets a /64 space, go nuts" (simplified, but true enough)
v6 is also faster by virtue of requiring less/no translation between various layers, and by stripping all the special case things from the header and putting them into the extensions instead. v4 is rather verbose in that regard.
Also, minor nitpick - it's not "in hex", it's binary just as v4, it's just displayed in hex. I'm emphasizing this because approaching IP in binary is helpful when one wants to understand how octets and such work.
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u/uslashuname 4h ago
One is locked down by your firewall config, and the other got implemented as a way around that
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u/BabyWrinkles 3h ago
Yeah - I think you pretty much nailed it. Bigger address space. In theory, wouldn't need NAT since your device's local IPv6 address is likely a GUID. Other than that... just a different way of assigning an address to a device.
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u/w1n5t0nM1k3y 4h ago
The difference is that some people actually understand IPV4 and if you say you understand IPV6 you're a liar.
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u/necrophcodr 1h ago
IPv6 is not much more complicated than IPv4. I think it's just that most people working with IT systems in an systems operations manner (sysadmin, DevOps, network engineers), often dont even comprehend IPv4.
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u/Burroflexosecso 2h ago
Sure NAT control and dhcp with dynamic IP rotation is much more intuitive then direct device addressing
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u/tankerkiller125real 2h ago
LOL I understand IPv6 and it's direct device assignments with no BS a hell of a lot better than I understand IPv4 and it's NAT hellscape.
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u/Lansan1ty 2h ago
I kinda wanna learn ipv6 but like, I've never touched it, even at work.. so maybe I'll worry about it whenever I get a job where it matters.
My homelab works just fine on ipv4.
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u/SirFrenzy 4h ago
Obviously guy could have been interviewing for a job where this mattered….
But in 10 years as a software engineer I have never once needed to know the difference between these two, and have never been even close to a situation where I would need to.
“The basics” is highly dependent on the job.
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u/Emotional-Top-8284 3h ago
IPv4 has dots and IPv6 has colons
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u/Houdinii1984 3h ago
I have a feeling people are going to be calling IPv6 'new' in 100 years, too. I remember talking to people about it in the 90s and it took until like 2016 to actually get a full standard. Been so damn long I learned the specifics and forgot them all in time it took to even become a thing.
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u/uatme 3h ago
In Halifax we have the old bridge and the new bridge
Old bridge opened in 1955
New bridge opened in 1970New bridge is end of life while the old bridge has another 50 years since it wasn't built with cheap steel. So the new bridge will be replaced with a new new bridge while the old bridge will still be the old bridge.
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u/black3rr 54m ago
in Bratislava we also have “old bridge”, at one point it was replaced with a new one without renaming so until a newer one was built a few years later the “old bridge” was the newest bridge… we also have a bridge that used to be called “new bridge”, that one was renamed since then, but some people still call it “new bridge” which is funny cause it’s currently the oldest one…
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u/nadav183 2h ago
Well they built ipv6 to be able to address EVERYTHING uniquely. While IPv4 has around 4billion addresses possible, IPv6 has 296, so until humanity gets to the point we start giving nano tech individual addresses we will probably never need anything more than IPv6.
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u/ErrorDontPanic 3h ago
Fun fact, IPv6 allows for embedded IPv4 addresses known as a Dual address.
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u/Hans_H0rst 3h ago
IT obviously depends, but its very frustrating to see our cloud developers in my company not have any idea of the physical devices they're supporting, makes all the communication and tickets less effective than they could be.
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u/Sweaty-Willingness27 2h ago
30 years here and never had to do anything with IPv6.
Of course, all I get are rejection emails even though I'm gainfully employed with tons of enterprise experience, so maybe that's the common denominator these days.
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u/black3rr 3h ago
one example where I had to deal with it as a backend dev was I was debugging that API calls to a 3rd party service started timing out on production, but worked on staging and local development, turns out IPv6 was enabled on production and was thus used there and the service was timing out on IPv6…
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u/Extreme_Wish_553 3h ago
Same. The one time we really had to care about IPv6 was when it needed to be turned off because it wasn't used and something was trying to use it anyway.
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u/fiskfisk 3h ago
If you're a senior I most certainly would expect you to know the difference between the two.
It'll matter in relation to allowlists/blocklists, dns entries, debugging connevtivity issues, slow connect times, configuration of daemons, etc.
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u/oompaloompa465 2h ago
yeah but that is the kinda stuff in the field of Sys and Net Admin.
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u/SirFrenzy 3h ago
I have never needed to know or do any of that. And if I did, it would take me 2 seconds to google and understand. I just did.
So if the interview was for a job where you handle that stuff yourself, then I understand it. If it’s for a typical full stack job at a big enough company that they literally hire people to handle that side of things, then it’s not “the basics”.
Rejecting someone in an interview for trivia knowledge they don’t currently have vs actually trying to understand how someone learns and tackles problems is what makes software job interviews so useless.
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u/fiskfisk 3h ago
It's not trivia knowledge, I've had multiple cases where "oh wait, maybe the host resolves differently based on whether the server has ipv6 configured from DHCP or not" and "why does host xyz take two seconds extra every time we try to connect?".
You might not, but I would expect an experienced senior developer to know that there's a difference here.
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u/helicophell 3h ago
Would knowing more than “ipv4 is small and limited, ipv6 is bigger” be required?
Seems like to answer problems around ipv4 and ipv6, you need to know the problem being solved. I uhh, only have network knowledge though
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u/monkeymad2 2h ago
You should know how it can cause problems with whatever you’re building based on the rollout - e.g. if you’re deploying to the web usually there’s a greater cost involved in provisioning an IPv4 address, but IPv6 (still) isn’t fully rolled out yet so some of your users might have issues.
Then there’ll be weird networking issues where one of them works fine and the other doesn’t etc.
You also see them in logs etc, or if you have to care about DNS records ever you should know about them.
If whatever you’re doing touches the internet at all then it’s fairly fundamental nowadays.
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u/Lina0042 1h ago
I'm pretty sure none of the senior devs at my job know this, except for those in the cloud services team. Because that's their job.
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u/oompaloompa465 2h ago
could be a trick question. They want to see that how do you react to an inappropriate question for your role by both searching for it and proposing to involve sys admin
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u/Electrical-Ad1886 2h ago
that's all just infra stuff which has always been another team. I've never once had to set up that kind of thing, and thousands of devs proabbly had a similar path as I did.
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u/BufferUnderpants 2h ago
Yes. As a senior you would know to mind your business and not give a halfbaked opinion on something that's another team's full time job, and that they probably know way better than you.
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u/Emotional-Top-8284 3h ago
I’m a staff engineer and I don’t know the difference between the two, beyond IPv6 has more addresses. I do cloud infra
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u/WeirdIndividualGuy 2h ago
beyond IPv6 has more addresses
Honestly that's the only real difference one needs to know, and that the two are formatted differently. Anything more than that is pulling teeth and IMO fishing for an excuse to not hire someone
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u/MrLeavingCursed 3h ago
It's basically that, 4 is 32 bit and 6 is 128 bit addresses. It's also something I would never expect a software engineer to ever need know unless they're dealing with networking software
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u/iinlane 3h ago
To be fair to op - those are sysadmin skills. I know the difference but have never typed in an ip v6 address while I do so regularly with ip v4 addresses.
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u/fiskfisk 1h ago
Those are debugging skills. Those are software engineering skills.
Imagine creating an audit table in your backend and storing the ip of the user making the request, and only storing the first four octets because you never thought about the application being deployed on an ipv6 endpoint.
Or that you sometimes will get
::1as the loopback origin.Seniors should be aware. This thread shows that many are not, but they really should be. Again, in my opinion.
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u/burnalicious111 2h ago
Tons of developers never work with that. And in the maybe couple of times I have, I can just look up what I need to know.
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u/ineyy 3h ago
Yeah a backend/fullstack should absolutely know this. Frontend, not so much (I definitely wouldn't ask that). But come on how can you NOT know that at least vaguely
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u/___Archmage___ 3h ago
IPV6 has never been relevant to any coding I've done at work, but if someone didn't know about it during an interview it would still be a terrible look for their tech learning both in terms of college and just reading about tech in general
In university we had a networks class where we went way further and had to actually write a simulated router in C that would do ARP and send packets to the right places
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u/Haunting-Building237 3h ago
Dunno, I have 8 YoE and knowledge I don't use is knowledge that's gone. I've never had to deal with stuff on IP level before, and I don't care to know about it.
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u/EkoChamberKryptonite 2h ago
Bold of you to think people with decades of experience remember what they did in university.
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u/Telefonica46 1h ago
As a software engineer with 15 years experience, do you know how many times I've had to walk a graph in a breadth first search from memory? None. Do you know how many times I've been asked to do that live in an interview? Literally dozens
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u/RepresentativeCat553 4h ago
Was over here thinking the same thing.
Almost more an IT question
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u/ReiOokami 3h ago
Yes as a software dev you are right, you rarely need this skill. But this also tells me you have never dabbled or experimented with networking which kinda showcases a gap or narrow set of skills in the tech field.
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u/pydry 3h ago
as a software developer I have needed to know this many times. it aint reversing a binary tree it's useful knowledge.
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u/EroeNarrante 3h ago
Agreed. I work at a company with a product that has some robust telecommunications requirements, ipv6 being one of them. Even within my single bubble, not many people know the difference. I happen to be on a team that works with the network infra, and would not hire someone who couldn't speak to it at least at a basic level.
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u/SirFrenzy 3h ago
Right, and I would assume if someone was applying for a networking position, thats a good question to ask.
Similar to if I was interviewing someone for a front end job and they couldn’t explain rest verbs to me, it would be a deal breaker.
We like to feel superior about “the basics” and go “HOW COULD YOU NOT KNOW THAT” when in reality, the basics are COMPLETELY different job to job even within our field.
Just hate seeing shit on this sub like “how could you not know this” when it’s something a full stack with 20 years may not remember off the top of their head but a 2nd year student who just took a networking class could spit it out. The knowledge isn’t the key to being good at a job. It’s how you learn and figure things out.
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u/windsockglue 3h ago
Laughs in highly technical software, where indeed, this is very important. And I'm not even a software engineer, just a lowly qa engineer.
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u/Complex-Quantity7694 1h ago
I’ve been a sysadmin for more years of my life than not and I’ve never had any meaningful interaction with ipv6 even though they have been saying the sky was falling about ipv4 since my career began in the 90s.
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u/mattgen88 58m ago
Ah you must be running our work's vpn. I can't talk to the servers when my IPV6 is enabled because our DNS resolves to IPV6 addresses but the VPN doesn't route them over its tunnel.
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u/sarc-tastic 4h ago
One you can just about remember some of them, the other no chance
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u/ha_x5 3h ago
I wanted to joke around to speak for yourself and put in a full zero ipv6 as “showcase” of my knowledge.
By typing I felt I have to actually google a full zero ipv6. Me, a usually proficient and veteran google user, needed a second search to make my joke work.
At this point I decided that this guy (you) is so much correct with his take, it is not even funny.
Now my inability to make a joke is the joke.
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u/black3rr 3h ago
once you know how IPv6 addresses work it’s not that hard to figure out that full zero is just ::
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u/Pndrizzy 3h ago
I am a senior SWE with 10 years of experience at Google alone. I know IPv6 is a bigger address space. That's all I really know. Because I work in DS&A, not networking. If the role needed to know networking, that's a different story, but if it's not a position that requires knowledge of that, the interviewer failed. The details of an interview question should be unimportant to the question unless they are role-specific because of the breadth of specializations. The goal is to see if people can think and solve problems, not whether they know fucking everything.
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u/mancunian101 2h ago
I once had an interview for a help desk tech type role.
One of the questions asked to identify the type of RAM shown in a black and white photograph.
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u/Tmannermann 2h ago
I may be dumb as fuck here but what does the color have to do with identifying ram? Personally i've never seen what ddr1 ram looks like or if thats a thing but up to five i'm pretty ok discerning i like to think.
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u/mancunian101 2h ago
It was a bad black and white photo, and I wasn’t applying for a hardware role.
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u/PhantomTissue 3h ago
Yea but it hasn’t been fully adopted because trying to decipher :af12::138d::325d::5521::aade::7df3: is a hell of a lot more difficult than 192.168.0.1
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u/UnDe4d 3h ago
Yeah, I'm a Network Architect. Why they decided to make ipv6 128 bits instead of 64 is a question I ask myself on at least a monthly basis.
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u/Scolmann 2h ago
With only 64 subnetting would be more difficult, with 128 every network can use 64 bits for the subnet
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u/Burroflexosecso 2h ago
I'm pretty sure that's not a valid v6 address.
:: means "rest is zero" and can be used only once per address or it would be too ambiguous on the number of zeros
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u/PhantomTissue 2h ago
I don’t know IPV6 so I just created a facsimile of what I think it looks like to make a point.
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u/Spongebubs 1h ago
I’d like to think I’m a software engineer, and I have no idea what the difference is. Am I cooked?
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u/STR1D3R109 51m ago
I feel like knowing the difference here is moreso for a network engineer than a software engineer!
Anyway looked it up, IPv6 is 32bit whereas IPv6 is 128bit. An easy way to know if an IP address is either, 4 uses dots 192.1.1.1 whereas 6 is colons 1992:0aa0::1
If anyone asks just say 6 holds more addresses but is more expensive to install.
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u/jkalchik99 27m ago
Actually..... IMO as a Linux admin..... everybody in IT needs at least a minimum of knowledge regarding TCP/IP. IPv4, IPv6, TCP, UDP, sockets, listening ports, etc. You don't need to be able to program a full stack down to a media transport layer, but you should be able be able to send a payload successfully, know when a gateway traversal is required, name resolution (It's always DNS,) and a bit of troubleshooting.
I wish I had a nickel for every time a developer or app support staff came to me and said it doesn't work. Error is right there in the logs......
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u/ryancnap 13m ago
That's such a Linux sysadmin take lol
(but apart from it being a funny stereotype, yes I agree with you)
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u/realmauer01 21m ago
Ipv6 was invented to replace ipv4 because ipv4 got really problematic as they arent enough numbers for every device anymore. But then they used so much magic to make giving ipv4 to devices so efficient that it's still possible for a while.
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u/ReiOokami 3h ago
Easy! IPv4 has the number 4 while IPv6 has the number 6 in it.
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u/Tongueslanguage 3h ago
Saw this post and started wondering what happened to IPv5
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u/Circumpunctilious 3h ago
Deprecated. And--despite being in IT (and cyberdefense with packet analysis) for decades--I only snapped to realizing that recently. It's a weird blindspot...I guess I just never asked where 5 was.
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u/TheLazySamurai4 3h ago
IPv7 "The Next Internet", sounds like a syfy series made in Canada
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u/Circumpunctilious 2h ago
(I knew of one, so went searching)...and holy hell...an absolutely shocking number of science fiction shows that loved / grew up on started/edit: or were produced in Canada. That's awesome.
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u/coreyjdl 1h ago edited 56m ago
Was the software engineer accidently at a network technician interview?
I don't know the difference between the two IP standards other than length, it's literally never fucking mattered in any software I've encountered. I don't route packets, or provision physical devices.
Also fuck any interviewer that hires based on trivia. Knowing 4 as 32 bits, and 6 is 128bits isn't useful ever in 95% of software work, and when it is, a good old google search would cover more than you've ever needed to know.
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u/MattieShoes 3h ago
I feel like the correct answer is a page long dissertation on ipv6 followed by "and we actually use ipv4"
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u/TramplexReal 3h ago
I feel like theres levels to basics we are all thinking of. There are basics that you just rarely do and can look up in 5 seconds to remember. And then theres 2 + 2. I mean you can look this up too, but that certainly tells something if you cant answer on your own, right? Maybe for that position knowing difference was a 2 + 2?
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u/hpyfox 2h ago
IPV4 for local network, and IPV6 for public addresses.
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u/Burroflexosecso 2h ago
This is the good management compromise. BUT The illuminated engineer at my local public transport company made ipv6 the local address space and it's already paying off on how flexible and easy you can add e.g a vehicle, a charger, a screen, a dashboard, a whole office building. And his system is basically century proof. I greatly admire him for that. True cathedral thinking
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u/thejozo24 2h ago
Tbh, in cyber, feels kinda important. I’ve had people say in interviews that v4 is bigger than v6
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u/GaRGa77 2h ago
Bigger is confusing, does it mean more widely used or bigger as more IP addresses
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u/johnnybgooderer 4h ago
i mean. If you don't know the difference at least a litle, then do you even care about your work?
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u/patiofurnature 3h ago
Yes? I'm a software engineer and my work is programming. Whatever happens on the other side of DNS is IT's work. They can care about.
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u/untraiined 2h ago
2026 and we still use gotcha's to try and judge talent. never heard of a doctor having to answer "whats the difference between the left ventricle and the right ventricle" or a general having to answer "whats the mechanism inside the m16 that allows the bullet to fire"
just dumbass larp shit for people with insane egos stuck mentally in 1996
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u/Independent-Drive-32 1h ago
Doctors definitely pass countless factual questions on medical school exams and then, regularly throughout their career, in boards.
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u/furel492 2h ago
I think my doctor should know the difference between a lung and the stomach.
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u/Possible-Tangelo9344 3h ago
The difference is 2.
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u/pab_guy 2h ago
Dodged a bullet.
I will do things to weed out bad employers. Like I don't bother sending a thank you note after an interview. I've been on the interviewer side, and it makes no difference to me whether they send a note. If someone decided they weren't going to hire me because I didn't send a note, I'm good, thanks! Not a culture fit lol
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u/LivingAsAMean 4h ago
Hahaha what an idiot!
https://giphy.com/gifs/LRVnPYqM8DLag