I have to say right off the batt, I'm by far no networking guru. I'm for sure very good with servers, but some of this networking stuff is somewhat out of my league like RDNS.
If I check my domain using the Pingdom tools (http://dnscheck.pingdom.com/?domain=techcores.com), I noticed that it's complaining about my reverse DNS record (server1.techcores.com.27.106.38.in-addr.arpa) that I had my host set.
On the other hand, I do know why it's complaining about too few IPv4 name servers though. That's not a problem. It's only one server hosting the site so if the server is down, a second IP won't do any good...
The error is the following: Reverse for 38.106.27.103 points to an unknown host name (server1.techcores.com.27.106.38.in-addr.arpa). The PTR record for the address points to an unknown host name.
Does anyone see any problems with my configuration?: http://grab.by/grabs/0445d304733ac8952cd8ae9ed447edfc.png
Thanks for the help! Virtualmin has saved my butt a few times when making some quick and rather critical changes.
Yeah, that is indeed very odd data for a PTR record. :)
Usually, A records resolve hostnames to IP addresses (techcores.com -> 38.106.27.103). Conversely, PTR records resolve IP addresses to names. To fit in the "DNS hierarchy system", the IP address is reversed, and the "pseudo-domain"
in-addr.arpais appended.So, in this case, the PTR record for
103.27.106.38.in-addr.arpashould resolve to "techcores.com", or a system under that, like "server1.techcores.com". It should (must) not resolve to something ending in "in-addr.arpa"!Are you hosting the reverse-zone yourself, or does your hosting provider do that for you? The nameservers responsible for the IP in question are
ns0/ns1.wansecurity.com.If those are your systems: What is the content of your zone file for
103.27.106.38.in-addr.arpa?Thanks for responding quickly! I was betting I had some odd data for my PTR record, but quite frankly, I have no idea on how to set it up.
When you say the PTR record, which in my case is 103.27.106.38.in-addr.arpa, needs to point to a site that can resolve, like server1.techcores.com (which does resolve by the way -- that's one thing I do know how to set up), is it not set up the way it should be? It might be easier if Virtualmin offered some kind of simple interface to set up the RDNS record. In fact, I see that on many sites they neglect to set it up -- probably because it's too complex in understand how it works.
The DNS system is fully hosted by me. The IP's nameservers are under ns0/ns1.wansecurity.com, but the name servers for my domain (ns1/ns2.techcores.com) itself are powered by BIND9 running on my server, which Virtualmin sets up.
The "wansecurity" security system is not mine; I believe my host did that. I did tell my host to set the RDNS to server1.techcores.com. I think there's nothing wrong there, but then again, I'm new at hosting a DNS server.
In any way, this is for sure not made for a starter with DNS like me...
Well, several things seem fishy there. :)
First, Webmin does have a function (in form of a combobox under the address) to set up PTR records automatically when you add A records to a zone. The reverse zone needs to already exist though.
In Virtualmin... Not sure at the moment. Will skim through the config if I find something there.
Currently, it appears like your hoster who is controlling
nsN.wansecurity.comdid not set up a proper delegation to you then... Thein-addr.arpazone that contains your IP is still served by them.How did you create the BIND config that you have in your screenshot? Through Virtualmin, or manually?
At least it's set up wrong and not some major issue... that's good news! :)
Hmm, interesting that there is a tool to set up the PTR records for you. I didn't see it in Virtualmin, but there's for sure a lot of settings in there. Virtualmin is just an extension of Webmin though; I'm thinking it should still have it though.
Interesting. So that's most likely why you can still access the site without any problems. It seems that it's working without the RDNS though -- but I know you need RDNS set up for e-mail and things like that.
One question: the in-addr.arpa zone and the RDNS, are the same thing, correct? Sorry if it seems like such a basic question.
For the BIND config, I set that up manually by creating a master reverse zone through the Virtualmin/Webmin BIND9 server interface. So basically, through Virtualmin.
Something just comes to mind. A colleague of mine, who's administering the nameservers for a German ISP, lately told me that sometimes he uses a "dirty trick" to allow reverse-DNS delegation for single or few IP addresses. Since customers rarely have a whole /24 subnet, they cannot delegate control over a whole /24 PTR zone to them.
To delegate single IP addresses, they'd use an "intermediate hostname" in the PTR record similar to what you're seeing there for your IP. The customer then can create a CNAME entry in their nameserver, pointing the intermediate to the actual hostname.
It would seem that your hoster tried to do something similar, but something got incorrectly set up in the process. Because the name that the PTR of your IP resolves to cannot be found, it has no A or CNAME, not even an NS entry.
Interesting. Seems that there's no standard way to set up an RDNS then... that makes this just even harder.
When you mentioned that the PRT of my IP resolves to cannot be found, which not even having an A, CNAME, or even an NS entry, are you referring the the "server1.techcores.com" on my end, or something on my host's end?
Wait, I'm thinking I'm getting this. Should the PTR entry be set up as "103.27.106.38.in-addr.arpa" and not "server1.techcores.com.103.27.106.38.in-addr.arpa"? So basically, the host sets "103.27.106.38.in-addr.arpa" to resolve to "server1.techcores.com", but they misconfigured it. Am I getting this now?
Now it might sound a bit awkward if I tell my host they set it up wrong. Would it be more than adequate to say, "I believe you set up my RDNS's PTR record of my IP address in correctly? Would you mind taking a look and correcting it if that's the case?"
Telling my host they did something wrong just feels odd because they should be the ones who know what they're doing...
This forum also badly needs a quote function...
Well there actually IS a standard way. :) It's just not easy to delegate control over single IP addresses to customers using the standard way. Managing whole /24 subnets is much easier, namely identical to managing forward zones.
Sometimes hosters offer web interfaces where customers can configure the reverse DNS entries for their servers. My hoster does it that way e.g. For every IP that my server has, I can enter the desired hostname in the management web site.
On the hoster's end. Only he can tell the registry who is responsible for nameservers under their in-addr.arpa subdomains.
Well... yeah, partly. :) Yes, they could do that, then the RDNS would resolve correctly. But then it is no longer under your control, and the hoster needs to set it, either by you telling them to enter there what you want, or by offering one of the aforementioned web interfaces for you to enter stuff there.
That is true, for the most part. There are also just humans working there, and humans make mistakes. :) Though as I said, it appears to me that they set the PTR record intentionally to what it is, and that they tried to delegate control over it to you this way. Question: What exactly did you ask them to do that led to this kind of setup?
This forum also badly needs a quote function... They should implement TinyMCE... I've used it in some of my works, and it's very simple to use and write extensions for. :)
Well there actually IS a standard way. :) It's just not easy to delegate control over single IP addresses to customers using the standard way. Managing whole /24 subnets is much easier, namely identical to managing forward zones. That makes sense. I for sure don't need /24 subnets for my site, but they're a hosting company, they should be used to it using their "dirty" ways.
Sometimes hosters offer web interfaces where customers can configure the reverse DNS entries for their servers. My hoster does it that way e.g. For every IP that my server has, I can enter the desired hostname in the management web site. Unfortunately, my host doesn't do it that way; at least to my knowledge. They never gave me any control panel of some kind for DNS management.
On the hoster's end. Only he can tell the registry who is responsible for nameservers under their in-addr.arpa subdomains. Okay, that makes sense. They only control the in-addr.arpa subdomains for our IPs then...
Well... yeah, partly. :) Yes, they could do that, then the RDNS would resolve correctly. But then it is no longer under your control, and the hoster needs to set it, either by you telling them to enter there what you want, or by offering one of the aforementioned web interfaces for you to enter stuff there. How would it be no longer under my control? As of right now, I do understand my PTR settings are correct, but the hosts are not.
That is true, for the most part. There are also just humans working there, and humans make mistakes. :) Though as I said, it appears to me that they set the PTR record intentionally to what it is, and that they tried to delegate control over it to you this way. Question: What exactly did you ask them to do that led to this kind of setup? I actually quite simply said after some talking: "Yes, I would like RDNS enabled... please just make it "server1.techcores.com." That wasn't the right thing to say, was it? Sorry for being such a n00b now, I try not to be, but can you offer something to correct my RDNS issues? The only way to really learn this stuff is through someone else. So hopefully, this'll help someone else who stumbles upon this issue. Most threads on here that I found aren't per se helpful...
DAMNIT, the virtualmin.com server went down once more while I was trying to type my latest reply, making me lose what I typed. So I have to do it again...
The webmasters here really should see to it to get their service a little more stable.
To make things more clear, you should differentiate between Webmin and Virtualmin. Even though the latter is indeed "just an extension" of the former, mixing them up can lead to great confusion.
Okay, so you created that reverse DNS zone in Webmin. How exactly did you end up with that CNAME record in there? The odd thing is, it looks like a "correctly set up dirty trick" to me, if only your hoster had delegated control over
techcores.com.27.106.38.in-addr.arpato your server, then it should work. When I query your server directly, the CNAME is resolved correctly.And yeah, basically you can say that RDNS and the
in-addr.arpazone are the same. Or rather, RDNS is a generic term for resolving IP addresses to hostnames, and in-addr.arpa is the zone used to do that. For DNS itself, there is no difference between a "forward" and a "reverse" zone. The latter just happens to be under in-addr.arpa and contain PTR records.Yikes, sorry for what happened to your reply. Most of the time for me, if that happens, I can just go back and it saved all the data I typed for me. At least on Google Chrome and on my Mac.
Agreed, Virtualmin and Webmin are completely different. Mixing the two probably would do any good.
I was actually just following this tutorial to set it up: http://www.comptechdoc.org/os/linux/manual4/reversezone.html
Is it because they delegated the IP to "server1.techcores.com.27.106.38.in-addr.arpa" to make it not work? Server1.techcores.com is actually just an alias (server1.techcores.com. IN A 38.106.27.103). Would that be the cause of it?
Thanks for explaining DNS and RDNS in general. That makes much more sense now.
I just checked up on the RFC where "Classless IN-ADDR.ARPA" delegation is defined, and interestingly, it is exactly the other way round there.
According to the method described there, it should go like this:
The reverse zone at your hoster should contain a CNAME record to
server1.techcores.com.27.106.38.in-addr.arpa., and delegate control overtechcores.com.27.106.38.in-addr.arpa.to your nameserver by adding the appropriate NS records.Then you go and set up the
techcores...in-addr.arpazone in your BIND and enter a record there likeserver1 PTR server1.techcores.com.This way, when someone wants to reverse-lookup your IP, while expecting a PTR record during the initial lookup, will get a CNAME, saying "this PTR is found elsewhere", then they'd query the NS for the zone where the CNAME points to, get your nameserver, which in turn gives them the PTR they initially wanted.
That's the method described in the RFC, which makes a lot of sense to me. But the way it is currently set up, your hoster has a PTR instead of a CNAME. It strikes me now that you have a CNAME too in your setup. So either there is some strange other method of doing this classless IN-ADDR.ARPA delegation, which works the other way round, or both your hoster and this tutorial are telling nonsense. ;)
Actually, I'm a n00b too in terms of RDNS, I've never configured those zones myself so far. I've only used hoster web interfaces to do that. Anyway, the topic is interesting, and I'm usually a fast learner with those things. ;)
Fact at this time is that something is set up incorrectly. My suspicion is the PTR record at your hoster instead of CNAME. Then, this tutorial you used. Does it say why you should enter those CNAMEs in your reverse zone? I don't see how those make sense in terms of what you're trying to achieve.
If we don't find a solution now, I can offer to phone my colleague whom I mentioned before. I'm quite certain he has lots of experience with those things and can quite quickly say what's wrong and why.
Ha, join the club! DNS is tricky... why can't ARIN handle it all for us? :P
I think that's the case too. For the tutorial, no idea why it wanted for me to enter a CNAME.
So quite simply, my RDNS record should look like this: http://grab.by/grabs/1869503ee1e94e4d2a1eafc375d49799.png
And now I'm trying to figure out what to say to my host to correct it on their end. Should I say:
"Could you please set your reverse zone for my IP to contain a CNAME record to server1.techcores.com.27.106.38.in-addr.arpa., and delegate control over techcores.com.27.106.38.in-addr.arpa?"
Giving a web-developer (myself) to understand these DNS things is rather challenging. Ohh the world of the internet nowadays. We have to get through 10+ networks just to get to any website. :P
Well, theCNAME was, in my opinion, superfluous. I suppose the guys who made that tutorial just copy+pasted that from the page before, where they set that up for the forward zone (THERE it makes sense).
But the PTR must, on your end, read like
server1.techcores.com.27.106.38.in-addr.arpa PTR server1.techcores.com.You might ask your hoster if it is intentional that they used a PTR record instead of a CNAME to delegate the RDNS to you. And why there is no NS entry pointing to your server. My assumption is they'll then say "Oh, you're right, sorry, our mistake, will be fixed right away". Or, they might explain you why they did that and what you need to set up to make it work. :)
No one can expect everyone to be nameserver experts. :)
Another hint, to avoid mixups: "Delegation" refers to NS entries that say "this subdomain of the zone being defined can be found on another nameserver". A CNAME alone is no delegation, just a "the name you asked for is an alias for another name".
That makes sense that they probably copied the tutorial from the forward zone. It does make perfect sense there... and I ask myself why is that #1 in Google search results.
Got it! Thanks! I changed the PTR (http://grab.by/grabs/10505693d6d23b6bed0b74607aa92d54.png) and I'll shoot my host a message very soon.
Ohh yes, these days, the internet in general is pretty complex stuff. But that's why we have awesome programs like Virtualmin! Blah... cPanel. :P
Ohh, so I guess that's why they say to delegate the NS entries. Delegating a CNAME sounds a bit awkward too anyways. Like you said, it's just an alias just like "www".
Speaking of which about these forums, I'm thinking they should add karma onto here. Because I would for sure give you some for your help!
Sorry for "belated" reply... The server went down again for like half an hour. The third time today. Luckily I copied my message away beforehand this time. :-) Unfortunately, Opera only shows an empty edit box when I use the BACK function here, so I guess I'll have to do this COPY thing every time for now, until this thing gets a little more stable.
Screenshot: Yep, looks fine, except for a "." behind the in-addr.arpa. :) Might go bonkers without that. And amen to the Internet being complex. At least when you get behind the scenes of what's going on. And actually, even though DNS is already rather complex, that's nothing compared to how much stuff (hardware and software) has to play together so that you can fetch your email and browse websites. :)
The "official term" is nameserver delegation, yep. And thanks for your "virtual Karma"! :-)
That's fine. I really think the Virtualmin guys, I'm thinking one is named Joe, needs to do something about the server. I'm a server guy myself (well, having an unmanaged VPS says a lot right there) and I know how it is when your server goes down.
I guess we just need to get in the habit of saving our posts. I typically copy and paste these types of things right before I submit the form. I don't trust them because sometimes they can through the weirdest errors back.
Ohh, woops! I forgot that period after the in-addr.arpa. It's for sure beneficial that I do understand how the internet works, but then again, there are those really complicated things like what ARIN does for us. Hardware and software is huge. I'm a server guy myself even having a home server (running Debian Linux of course -- I'm a Debian guy), and to be quite honest, it's a pain to manage. There are those mandatory updates that can mess up suEXEC so much that Apache is barely working, having MySQL randomly shut down, and having your mail servers (Exim & Postfix in my case) just randomly stop working. Practically anything, even the slightest time change when the time server changes the system's clock, can get your services to crash. It's a pain for server admins, but until they make software that can run itself, we're going nowhere.
Anytime! Thanks again for all of your help!
Yeah, I've read the names "Joe", "Jamie" and "Eric" by now. :) According to an entry on the issue tracker, that's the whole team actually. So in fact, they're doing quite a job, managing all this with three people.
I'm also operating a server - a VMWare virtual machine host with currently 12 active VMs (Windows Server 2k3 and Ubuntu Server).
So, not intending any insolence... If the VMin people could use some support concerning hosting, I'm here and willing. :) I'd think though that the coder team of something like Virtualmin know themselves, all too well, how to get hosting services and set up servers. :)
Yeah, I've read the names "Joe", "Jamie" and "Eric" by now. :) According to an entry on the issue tracker, that's the whole team actually. So in fact, they're doing quite a job, managing all this with three people.
I'm also operating a server - a VMWare virtual machine host with currently 12 active VMs (Windows Server 2k3 and Ubuntu Server).
So, not intending any insolence... If the VMin people could use some support concerning hosting, I'm here and willing. :) I'd think though that the coder team of something like Virtualmin know themselves, all too well, how to get hosting services and set up servers. :)
Ohh wow, they're doing a really good job. It's hard to run even my site let alone a larger site like this.
Awesome! Seems that you like Ubuntu! I try to stray away from Ubuntu as my server mainly because it's just too much of a memory hog compared to Debian. Once you have Apache, MySQL, Bind, Exim, Postfix, and all the other services going, I tend to feel that Debian uses less memory. I would say though, Ubuntu is more up-to-date than Debian is. But we all know why that is.
Agreed, if they need some help, I'll be more than willing to help them. Although I am a student, so I'm very frugal with what I spend. Well, all Webmin/Virtualmin is that it's simply a wrapper for all the commonly used open source programs. And for such a small team creating it, I'm sure all of them are experts by now with doing things without a backend. And actually, what's great about Virtualmin/Webmin, is that if you don't need it, you can simply shut it down and having your server still working just like it did before... I'm pretty sure cPanel can't do that! :P
I finally found that error you were talking about: http://grab.by/grabs/87e8196fee731f04309295c4f968d49c.png
I wonder if the Virtualmin team ever tried Nginx instead of Apache. Quite honestly, I love Nginx a lot for its extreme speed and stability compared to Apache.
I just phoned with the colleague I mentioned, who's administering the nameservers for a considerable German hosting provider, and he confirmed my assumption, that the original IN-ADDR.ARPA zone at your hoster needs to have CNAME entries, plus in this case NS entries, and your zone needs to have the PTR entries.
So with this info, you can ask your hoster why they configured what they did. :)
Thanks for clarifying that!
I contacted my host and they said they did set it up right, which is odd. They said they're looking in to it so let's see what'll happen.
Thanks for the help!
Yeah, tell me how this turns out. I'd like to see them either change their setup to what my colleague and me think is correct, or explain to you how their version of IN-ADDR.ARPA delegation is suppose to work. :)
I've been talking with my VPS provider, and I think I found the issue.
They said they added this to their setup: "103 IN PTR server1.techcores.com"
While being a novice at RDNS, I'm thinking the ending period is something they forgot. :D
I've sent them a message about it and I'm thinking this will solve all of my problems.
Thanks for the help!
Yes, you got that right, they most definitely forgot the ending period. Without that, the domain of the zone file they're configuring is added to the entry. :)
So they actually were not trying to set up a CNAME delegation to you, but just wanted to manually enter the hostname you requested to have for your IP into the zone file.
Yeah, thank Lord I found the problem! :)
I'm not too worried of them setting up a CNAME delegation. As long as it works, I'm fine. Besides, RDNS is really used mainly for one thing (at least what I know of)... e-mail. :P
Checking hostnames during email delivery is the prime purpose, I'd agree there, yeah. Other than that, it just looks niftier (is that actually a word? ;) ) if you have your IP point to something fancy than to some generic hoster-chosen customer hostname. :)
Basically for 'verifying' the source of the e-mail address. But it does make it look more authentic per se.
Apparently it's a word :P -- http://dictionary.reference.com/browse/niftier
Even after a week, my RDNS is still not working. My host says it's my end but I say it's theres.
They're offering no help once-so-ever. And quite honestly, I'm lost on what's wrong. They don't host their own DNS system so I'm forced to use my own. They offer no support for this even though it's something that could be wrong on both of our ends.
I'm sick and tired of this. I appreciate all of your help, but apparently my host is not willing to work with one of their own customers.
(http://www.webhostingtalk.com/showpost.php?p=7115759&postcount=14)
Well, it is a fact that whoever operates "ns0/ns1.wansecurity.com" still has an incorrect entry in their zonefile. Your IP still resolves to
server1.techcores.com.27.106.38.in-addr.arpa., they probably still have that "." missing at the end. There is nothing you can have configured wrong there, since you don't operate the correspondingin-addr.arpazone.All I can say is you should contact them again and tell them what you think about their service. And if you want a hoster who listens to what his users tell him, ask me nicely, and you might have a VM on my ESXi host. Including correct RDNS entry, and secondary DNS on one of my VMs (since your two NS point to the same IP, which is not the right way to do it really). ;)
That's what I even said to my host. I mentioned that the pseudo domain isn't even controlled by me and it's pointing to the wrong place.
I'll contact them again and see what they'll say.
Quite honestly, and for sure after all of my troubles, I would love to host with you; especially for your offerings! Having a secondary DNS is important for lots of reasons, but my host charges too much for another IP. I know it's wrong to have the two name servers pointing to the same IP is wrong, especially because I get no latency out of that, but I'm just not willing to pay that outrageous fee per month for another IP.
Feel free to shoot me an e-mail in about hosting with you! http://grab.by/grabs/cad0ea5408e9ae4db1c082b0c0cb7473.png
Sorry for the un-readable format; I just don't want any bots to read my e-mail address. :P
Thanks for the help! I guess in the long run, you get what you pay for... if you want to know how much I paid, I'll mention that in the e-mail. I just don't want to mention it here. :D
Edit: I just contacted my host about the issue. Hopefully they'll correct it. :)
Let me know how it turns out. :) Usually service providers invest a little more effort when they're about to lose a customer. ;)
It's of course sad though that they are unable to fix such a simple thing right away and let you wait for a week.
Will do; I'll be sure to let you know. What's ridiculous is that I've used four hosting providers for my site now. One of them were very big -- InMotion Hosting.
It is rather sad to see them let me wait a week to get this fixed. It's just disappointing; I know some e-mail providers are putting our e-mails in the spam folder, like Windows Live Mail (I really wanted to say Hotmail there...), and I'm betting it's because of my RDNS issue.
On the other hand, the Virtualmin guys should really take a look at all of these 500 server errors. Maybe they need to get some Apache and MySQL slave servers to offload some of that work.
They fixed it! Wow, it shouldn't of been that long. :D
Finally. :)
(Duplicate post due to 500 server error - deleted.)