I would like to create a subdomain off of my main domain for accessing my raspberry pi at home. My domain register company charges £10 for every subdomain so I thought there might be an easier (and cheaper) way of creating one. It would also help if I knew a little more about them and how they are created.
DNS is built off of a hierarchy for scale-ability and/or for granularity.
If we take the a domain like www.stackoverflow.com. and break it down, here is what we get.
www - This is the host portion of the domain. It is either an A record or a CNAME and eventually points to an ip address.
stackoverflow - This is one of the domain levels. It has it's own DNS servers and config managed by the stackoverflow team. This allows that team to manage the entries specific to their needs.
com - This is called a TLD (top level domain). All other domains that end in .com have an entry on the "com" dns servers.
. - This is called the ROOT. There are 20 somodd root DNS servers scattered around the world. These servers are used to identify where the .com, .org, .edu, .gov, etc dns servers are.
From a client perspective what happens when you query www.stackoverflow.com is:
You query the . name servers to ask where the com dns servers are.
You query the com dns servers to ask where the stackoverflow dns servers are.
you query the stackoverflow dns servers to ask where www is.
A subdomain simply means that you add an additional layer of DNS servers in the mix so that you can add more scale-ability and/or granularity to the mix.
For example, if our dns name is: www.foo.stackoverflow.com we would now have the foo dns server layer.
Having said that, I do not think that you need a subdomain. You probably just need an additional DNS A record or CNAME. For example:
raspberry.stackoverflow.com instead of raspberry.foo.stackoverflow.
They should not charge extra for additional host entries (A record or CNAME), only for subdomains.
Related
We are whitelabeling some website software, but in order to use it, our clients must point their domains to the software's nameservers. We'll say ns1.softwareco.com and ns2.softwareco.com.
Since we're whitelabeling, I don't want our clients to see Software Co's name in the name servers.
I could easily mirror Software Co's DNS settings, but if Software Co updates them in the future, my settings would be incorrect.
Is it possible to just point my nameservers ns1.whitelabelco.com and ns2.whitelabelco.com to Software Co's nameservers?
Your best way of achieving this is to follow the lead of other companies.
For example, if you look at how github allows the configuring of custom domain names for their pages product. Which is whitelabelling in effect.
The two options you have are basically, that you have a static IP address that will last for the lifetime of your service. Which would mean you would need to buy that address, complete with a contract to ensure it didn't need to be changed. You could place that address infront of load balancers etc, so it could be directed to multiple servers at the backend (even multiple locations)
The simpler option is to offer a CNAME redirection to your clients.
You tell your clients that you have service.example.com and they should point their servers to that with a CNAME record. so their clients will see www.domain.com but that will be redirected to your site.
The downside of a CNAME record over an IP Address, is that the end user can see that it is a whitelabel product. The problem is that DNS is an open system, and no matter what you do with it the end user will be able to see what you've done and find out that you are hosting that site.
The only way around that is to use an IP Address.
I'm trying to learn as much as possible about DNS, and so far I've read most of:
http://www.zytrax.com/books/dns/ch8/soa.html
and all of:
http://computer.howstuffworks.com/dns.htm
I understand that SOA and NS records contain info about the authoritative name server for a domain, but as these are just DNS records, how does the rest of the world even know where to get them?
I assume it starts at the top-level-domain (.COM .NET .ORG, etc) servers. So they must contain a SOA record for my domain? If so, how does that get there? I imagine only registrars like GoDaddy and Network Solutions are able to update those? If they contain a SOA record, why does my DNS server (that I host), need one also? I think there must be something, maybe in the domain registration records (outside of DNS?), that I'm missing.
I think I've got a pretty good understanding of most parts of the DNS system, after reading lots of articles.. but I haven't found any that answer this part, in a way that I understand it.
For example, GoDaddy and Network Solutions both let me change different options (in their web UI) to "host my own DNS server". If these options remove them from the process, so DNS servers never need to query them again, and instead query my server directly (this is what I want, no dependency on GoDaddy/NS)... when I make these changes, what (at the DNS level or otherwise) is GoDaddy/NS doing? Are they asking the top-level-domain servers to update some DNS records for my domain?
Short answer is yes. Godaddy will take care of updating your the TLDs for you. Your other assumptions are also correct except for one small detail...
DNS starts with the "root" domain and then goes to the TLDs (top level domains).
www.somedomain.com. actually brakes down like this:
. The root name servers
com - The TLD name servers
somedomain - Your NS servers
www - The host portion of the dns name.
Setting up your own DNS server is a great way to understand DNS better. Good luck!
So they must contain a SOA record for my domain?
Multiple answers possible, depending on the scenario:
delegated 2nd level:
No; the start of authority of your domain is usually at your level, so the SOA for you.cf is (only) in your nameservers. Same as the SOA for .cf is only in the nameservers of .cf, and not in the root-servers. In case your nameservers are within the same domain (i.e. ns1.you.cf in case of you.cf) then glue records are needed. This means that registry that's operating the TLD's nameservers will insert a A and/or AAAA record with the IP of ns1.you.cf in the TLD zone. Normally you (the registrant) set this in the interface of your registrar.
undelegated 3th level:
No; if your domain was sub.you.cf - but sub.you.cf wasn't delegated (no NS records exist for sub.you.cf) then the SOA is probably at you.cf. Unless...
undelegated 2nd level:
Yes; if you register a domain without having it delegated (no NS records exist for you.cf) then the SOA is at the .cf nameservers. Although most registries run delegation-only zones, some don't. Example: when you use url-fwd'ing in .cf. The SOA then is at the cf level.
I have inherited a web server that is hosting 5 websites for my client. Call them domian1, domain2, etc I just discovered that all the domain nameservers for all 5 domains are set to ns1.domain1.com and ns2.domain1.com. The single server is running the DNS for all the domains including domain1.com. ns1 and ns2 are both pointing to the same web server.
Aside from the fact that there is no redundancy, and the domain1 name servers are using the DNS to resolve their own IP's, why would anyone do this? Am I missing something?
There are two options when creating NS records for zones:
1) Set the NS record of each zone to point only to itself. Hence, domain1.com would get ns1.domain1.com, etc. The advantage of this is that the remote site doesn't need to do a cross reference to somewhere else and go look it up too. EG, if you have domain1.com's NS records pointing to ns1.domain2.com, then a lookup of the NS records for domain2.com have to be checked too to ensure it has the right location to go lookup where ns1.domain2.com really is. You could imagine the case where domain2.com's NS records point to domain3.com's name servers... This is obviously inefficient and results in a lot of unneeded chasing. So... pointing entirely internal seems like a no-duh, right! Less chasing! But... it also means you need to keep com's notion of your name servers in sync with your notion of your name servers, and when you add or remove them and/or change the IP addresses, you need to notify your com (through your registrar) that things have changed. (tech speak: update com's notion of your glue records).
2) Add an NS record pointing to an external server. This is common for server farms that sell you DNS services as part of their transaction as your registrar (ie, where you went to go buy domain1.com). They set your NS record to something like "ns1.godaddy.com". In your case, the previous zone owner set the NS records to all point to the domain1.com zone. This is actually helpful when you expect to change your address in the future. Rather than have to go change the IP address in all 5 of your zones, you only change it in domain1.com's ns1.domain1.com record and you're good to go. The other zones don't need to be touched. Yay! It's even more yay-full when you are managing 100 zones.
So, there isn't a right or a wrong here... It's a trade-off and different administrators do different things. Feel free to change it to the other model if you don't mind the zone-editing maintenance if you ever change anything. Personally, it's what I do when possible too: I like them internally self-contained. But then, that's also when most people fail to update the parent's glue records to match and there are tons and tons of zones in the world that are out of sync for exactly this reason: "oh, I'll do that tomorrow".
Ok, in a nutshell, for my own reaons, I am trying to "build" a solution that extracts my DNS from the location / company where my webserver is located. I need to be able to make DNS changes on the fly for my domains. I have nameservers set-up for the webserver, on the webserver. I basically want to know if I can point my domain registration DNS details, to lets say, a DYN.com dynamic DNS address, and have that dynamic address setup to just forward all traffic onto my nameservers on the webserver.
This way, I can change the dyndns "pointer" if you will, to any other webserver/nameservers immedietly should the need arise.
P.S. I know a dynamic address probably won't work, and If I have to go for a paid up service with DYN, thats fine, but I don't want to create all the records on DYN. I just want it to forward any requests to the actual ip of the name server on the webserver.
I.E.
Domain NS1 -> Dyn.com Record 1 (no specific domain records) -> ns1.mywebserver.com
Domain NS2 -> Dyn.com Record 2 (no specific domain records) -> ns2.mywebserver.com
Can this be acieved, if not, do you get what I am trying to do, and are there other ways of doing this?
I ideally don't want to create a dedicated linux VM somewhere to manage the DNS.
Thanks in advance.
I think my other question, posted after this one, solves this question.
BIND . Registrar says it cant find the nameserver. nslookup shows the domain is being handled by bind
Cheers
I was wondering if it's possible to dynamically add subdomains that point to dynamic IP addresses, and how I would go about doing that? In other words, "how is dyndns/no-ip implemented" :-)? (The part I don't get is adding/changing the DNS entries... I understand how the client sends a packet every few minutes -___-). I can tell all my users to just use DynDNS/No-IP, of course, but having it integrated with the application would be much cooler.
Thanks,
Robert
To be able to directly update/control where a domain/subdomain resolves to, you must have your own name server. When you register a domain under a TLD (for example, .com), that TLD has a nameserver. Anytime a client needs to look up the IP to something.com, they ask the .com nameserver where to find the nameserver for something. That nameserver in turn returns data about the domain or subdomain.
When you register a domain at a place like GoDaddy or Network Solutions, and you use their online tools to point your various subdomains to IP addresses, you are creating entries on their nameserver. When a client requests your domain, the root nameserver tells them to check with GoDaddy's nameserver. If you look through the configuration options of your registrar, you'll generally find a place to specify your own nameserver instead of entering domain IPs. Setting that will tell the chain of nameservers to defer resolution of your subdomains to that nameserver. Obviously at that point, having direct control over the mechanism of name-address resolution, you can do whatever you like.
Here's one list of open-source name servers. There are many others, ranging from free OSS to custom, proprietary and very expensive. Technically you could also write your own, as BIND is a public, standard format.
As you've partially said, the way DynDNS and other dynamic IP services work is that they update their server's DNS records based on a heartbeat from a client every few minutes.
The trick is that they use extremely short TTL times so that caches for the record expire very quickly and need to re-query the DynDNS server (which makes dynamic IP changes propagate quickly).
If you wanted to implement this, either find a DNS host that offers an API, or programatically update the DNS on your own server with a short TTL.