Koozali.org: home of the SME Server
Obsolete Releases => SME Server 7.x => Topic started by: judgej on February 04, 2009, 11:40:29 AM
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I realise that the SME Server does not use the local ISP's DNS servers for lookups, and that was probably a good idea when it was first set up (2001-ish), but is it such a good idea now?
When I change any settings on an Internet domain, for example to switch a website from one server to another, it takes quite literally days for my server to see the change. If I bypass the SME Server DNS by setting the ISP's DNS servers directly in my browser, then I see the change within hours.
So, is it time to make the SME Server's DNS lookup settings more prominant? Perhaps put them into the control panel, so you can switch to the ISP's DNS servers easily?
What do people think? This is probably only an issue to web developers, who are throwing domains around left, right and centre.
If there is any interest, I'll raise it as a feature request (but it's not something I'm going to battle if I'm the only one hitting these issues of slow DNS updates).
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I always assumed that djbdns used the root name servers by default.
I read somewhere years ago that the root nameservers use a ttl of 3 days for the root domains - ".com", ".org", ".net", etc - which can result in long delays in DNS propagation even if the ttl for your specific domain is set much lower.
Does your situation improve if you restart the dnscache service on the SME server?
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This is probably only an issue to web developers, who are throwing domains around left, right and centre.
If you are "throwing domains around left, right and centre" then you should be reducing the TTL of your DNS zone data before doing so.
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Does your situation improve if you restart the dnscache service on the SME server?
No, restarting and rebooting makes no difference. If the root servers don't know the answer, then the domains simply cannot be seen. It is a problem I have been aware of for years, but never quite put my finger on until now. Moving websites around from one server to another is not the kind of thing people do often, unless it happens to be the kind of thing they do, if you know what I mean (i.e. YMMV).
The SME Server setup sequence does provide a box to enter a *single* DNS server if required (up to four would be more appropriate IMO). If the server uses DHCP to get its public IP address, then I think there should be an option to allow it to get the DNS servers that it should use too.
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I read somewhere years ago that the root nameservers use a ttl of 3 days for the root domains - ".com", ".org", ".net", etc - which can result in long delays in DNS propagation even if the ttl for your specific domain is set much lower.
If that is true, then that would only affect additions and deletions of domains, not specific records within the zone.
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If that is true, then that would only affect additions and deletions of domains, not specific records within the zone.
*If* you can get at the TTL (SOE records) then yes, setting that low a couple of days before any major changes does help a lot. Sometimes, however, there is no access to the TTL and you are stuck with 24 hours.
Just to be clear, I am not talking about domains hosted *on* an SME Server. This is about domains hosted elsewhere, with the SME Server being used as the DNS on a local network (in server+gateway mode).
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I realise that the SME Server does not use the local ISP's DNS servers for lookups, and that was probably a good idea when it was first set up (2001-ish), but is it such a good idea now?
You would likely get some value doing some research on how DNS works. Here's a fairly non-technical doco that does a good job at explaining DNS: http://www.howstuffworks.com/dns.htm
You seem to be looking at DNS as if there is one big master database out there that stores all domain names and associated IP address. This isn't how DNS works.
If you are using SME like most of us, then you are probably using some kind of service to provide internet DNS for your Domain(s). It is this service that is causing the delays in your IP address changes, either due to settings related to your account there or with the service it self, or maybe a combination of both.
SME's caching DNS is just querying what's out there on the internet, just like your ISP would be doing. SME's DNS is quite good at doing this.
Charlie has given you the answer to your problem. Contact tech support for you DNS service and ask them how to modify the TTL settings for your domain(s).
The TTL settings in the root name servers have nothing to do with the TTL settings for your domain(s). Once you set the TTL for your domain(s) to say 60min, then no name server out there should cache the IP for your domain(s) longer than 60min, unless the name server isn't working right.
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No, restarting and rebooting makes no difference. If the root servers don't know the answer, then the domains simply cannot be seen. It is a problem I have been aware of for years, but never quite put my finger on until now. Moving websites around from one server to another is not the kind of thing people do often, unless it happens to be the kind of thing they do, if you know what I mean (i.e. YMMV).
SME is respecting the TTL entries for your domains. My guess is that the TTL is set to days.
The only reason SME would lag your ISP DNS is if that ISP is hosting the domains in question. If this is the case, then the ISPs DNS would be the authoritative name server for that domain, therefore the change would happen instantly (or as soon as your ISP updated its dbase internally). TTL would not come into play when query their name server directly.
The root name servers have no idea what the IP addresses are for your domains, because they aren't responsible for your domains. They only know where to tell the query to look next for the answer. You might end up with 2,3,4+ hops between name server, starting at the root name server, before you get an answer.
The SME Server setup sequence does provide a box to enter a *single* DNS server if required (up to four would be more appropriate IMO). If the server uses DHCP to get its public IP address, then I think there should be an option to allow it to get the DNS servers that it should use too.
You're looking at SME Server as if it were a regular workstation. There is no need for it to pull name servers from DHCP. SME has its own DNS.
The DNS entry in the SME setup is really meant to specify a DNS on your LAN that provides DNS for the hosts on your LAN in addition to forwarding requests to the internet. Most small to medium sized businesses (users) don't have, or need, multiple DNSs on their LAN, so providing an option for multiple local DNS servers would probably rarely be used.
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SME's caching DNS is just querying what's out there on the internet, just like your ISP would be doing.
That's where my problem is - this is not how it is happening. The SME server gets its requests from a *different* place than the ISP. It happens that this different place is usually slower to get updated then my ISP(s). I am sure it was the other way around years ago when SME Server was originally set up - ISPs were notoriously slow at updating their own caches. I am really just querying whether the assumptions made seven years ago are still valid.
-- JJ
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SME is respecting the TTL entries for your domains. My guess is that the TTL is set to days.
With a TTL set to a single day (24 hours) it has taken my SME Server almost two full days to catch up with a domain change. My ISP got that change within hours. It could be that the ISP is *not* honouring the TTL, which could be argued to be wrong on their part.
The only reason SME would lag your ISP DNS is if that ISP is hosting the domains in question.
Not the case in my recent experience. Registrar FASTHOSTS, web server 34SP and ISPs Virgin Net, BeThere Internet and Tiscali. All three ISPs picked up the domain change within hours. SME Sever took two days before it could even look up the domain.
The root name servers have no idea what the IP addresses are for your domains, because they aren't responsible for your domains. They only know where to tell the query to look next for the answer. You might end up with 2,3,4+ hops between name server, starting at the root name server, before you get an answer.
Yes, the issues I find, when doing an NSLOOKUP is that the lookup times out.
You're looking at SME Server as if it were a regular workstation. There is no need for it to pull name servers from DHCP. SME has its own DNS.
Yes it has its own DNS - just like any workstation has its own cache - but the issue is where it places itself in the world-wide hierarchy of DNS servers. I think it may be too high up the tree for its own good at times.
The DNS entry in the SME setup is really meant to specify a DNS on your LAN that provides DNS for the hosts on your LAN in addition to forwarding requests to the internet. Most small to medium sized businesses (users) don't have, or need, multiple DNSs on their LAN, so providing an option for multiple local DNS servers would probably rarely be used.
From what I remember looking at the config files of SME Server, it already has multiple DNS servers that it uses - about a dozen of them (though about half of those were out-of-date when I last looked). So, it already happens and is already used by everybody.
-- JJ
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I am really just querying whether the assumptions made seven years ago are still valid.
The DNS protocol hasn't changed.
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SME Sever took two days before it could even look up the domain.
Negative responses are cached as well, and those responses have their own TTL (controlled by the upstream server). You will see the name more quickly if you don't ask for it until after it has been created.
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Yes it has its own DNS - just like any workstation has its own cache - but the issue is where it places itself in the world-wide hierarchy of DNS servers. I think it may be too high up the tree for its own good at times.
It's not anywhere in the tree. The tree refers to content DNS servers, which start at the root, and follow delegation to other servers authoritative for subtrees. Your applications are interacting with the caching resolver, which doesn't sit in the tree, but walks the tree with queries.
I'd suggest you do some reading - e.g. "How the Domain Name System (DNS) works":
http://www.bytemark.co.uk/page/Live/support/tech/dnsworks
"How does DNS work?":
http://cr.yp.to/djbdns/intro-dns.html
"Notes on the Domain Name System":
http://cr.yp.to/djbdns/notes.html
If you think SME server's resolver is not working correctly, please provide details via the bug tracker.
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From what I remember looking at the config files of SME Server, it already has multiple DNS servers that it uses
Those are not DNS resolvers (which are the "DNS servers" used by client systems such as workstations). Those are just hints of where to start looking for the addresses of the root name servers.
- about a dozen of them (though about half of those were out-of-date when I last looked).
That pure BS, but if you believe it to be true, you should report details via the bug tracker.
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Yes it has its own DNS - just like any workstation has its own cache ...
Most workstations don't have a DNS cache. If they do have a DNS cache, there's only one correct way for them to work, which is to follow the protocol defined in the RFCs.
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That's where my problem is - this is not how it is happening. The SME server gets its requests from a *different* place than the ISP.
-- JJ
No it doesn't. There are other issues going on there that have nothing to do with SME.
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Yes, the issues I find, when doing an NSLOOKUP is that the lookup times out.
If you are querying SME's DNS and your lookup is timing out, then this is yet another indication that you have some issues going on with your configuration/internet connection, or network configuration.
Yes it has its own DNS - just like any workstation has its own cache - but the issue is where it places itself in the world-wide hierarchy of DNS servers. I think it may be too high up the tree for its own good at times.
A workstation is just caching results it queries from DNS you tell it to use. SME, on the other hand, is a DNS server and knows how to use the public Domain Name database that is spread over millions of Domain Name Servers all over the world.
SME's DNS, as it is configured by the default install, IS NOT a public DNS so it has no place in the "world-wide hierarchy" of Name Servers.
From what I remember looking at the config files of SME Server, it already has multiple DNS servers that it uses - about a dozen of them (though about half of those were out-of-date when I last looked). So, it already happens and is already used by everybody.
Those are the ROOT name servers. Every DNS uses this exact same list. This list rarely changes. This is where the name query begins -- that is a DNS asks one of these ROOT name servers first where to find the IP address for the domain is it quering. These ROOT name servers then send the quering DNS to another name server(s) for more information and so on and so on and so on until the domain you are querying is found.
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Those are not DNS resolvers (which are the "DNS servers" used by client systems such as workstations). Those are just hints of where to start looking for the addresses of the root name servers.
That pure BS, but if you believe it to be true, you should report details via the bug tracker.
It it's pure BS, what is the list of IP addresses in /etc/e-smith/templates/var/service/dnscache.forwarder/root/servers/@? They look like top-level DNS IP addresses to me. *Last time* I looked it was out of date. *Right now* it's not.
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If you are querying SME's DNS and your lookup is timing out, then this is yet another indication that you have some issues going on with your configuration/internet connection, or network configuration.
No. My Internet connections are fine.
SME's DNS, as it is configured by the default install, IS NOT a public DNS so it has no place in the "world-wide hierarchy" of Name Servers.
Between my PC and the top-level domain servers, is my SME server. How it that not part of the chain between my PC and the top-level domain servers?
Those are the ROOT name servers. Every DNS uses this exact same list. This list rarely changes. This is where the name query begins -- that is a DNS asks one of these ROOT name servers first where to find the IP address for the domain is it quering. These ROOT name servers then send the quering DNS to another name server(s) for more information and so on and so on and so on until the domain you are querying is found.
That's all well and good, but still does not solve the problem that certain changes to some domains take a long time (days) to get to the SME Server, when three ISPs I checked get the new details from *somewhere* much quicker.
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Between my PC and the top-level domain servers, is my SME server. How it that not part of the chain between my PC and the top-level domain servers?
No it isn't unless you've modified your SME Server to be a Public DNS. Your SME Server is just reading the DNS database.
Your PC does not know how to read the internet DNS database, so it is asking your SME Server to query this database and report the results. This does not mean your SME Server is part of that database, IT IS NOT.
If you feel there is a problem with SME Server's DNS, then report it to the bug tracker.
Beyond this, you seem to be more interested in arguing a point that you clearly have no knowledge in than listening to the free advise of people who do.
This is really going nowhere.
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No it isn't unless you've modified your SME Server to be a Public DNS. Your SME Server is just reading the DNS database.
I have my SME server in a virtualBox while tinkering with it and I am bothered by this statement because I am planning to deploy it in the Internet later on. I have several domains/subdomains configured via server manager. Ex. up.pem.tld, au.pem.tld, coc.pem.tld does this mean that these domains/subdomains will not be visible in the internet and would only be visible within my local network?
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I have my SME server in a virtualBox while tinkering with it and I am bothered by this statement because I am planning to deploy it in the Internet later on. I have several domains/subdomains configured via server manager. Ex. up.pem.tld, au.pem.tld, coc.pem.tld does this mean that these domains/subdomains will not be visible in the internet and would only be visible within my local network?
Correct. Is that not what the documentation states?
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If you want these domains visible on the WWW you need to setup DNS A records that point to your server.
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If you want these domains visible on the WWW you need to setup DNS A records that point to your server.
You need to do more than that. You need to register the domain with a domain registrar, and configure more than one Internet visible DNS server. I'm sure that the documentation covers the process.
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I'm sure that the documentation covers the process.
Some of it is covered here: http://wiki.contribs.org/SME_Server:Documentation:Administration_Manual:Appendix#Appendix_B._DNS
I'm sure google can answer any other questions.
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You need to do more than that. You need to register the domain with a domain registrar, and configure more than one Internet visible DNS server. I'm sure that the documentation covers the process.
It is not that I did'nt read the manual but that i have no experience when it comes to djbdns. Yes my top domain (pem.tld) is registred to a domain registrar.
If you want these domains visible on the WWW you need to setup DNS A records that point to your server.
Can't I do this setup of DNS A records in my SME server? Do I have to install another box just to house my BIND DNS Server? I am totally lost!
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ejay69
You can setup your registered domains DNS record at a good free service like zoneedit.com
You will need to get your current registrar to transfer the nameserver delegation to the nameservers that zoneedit use.
Your current registrar can also (usually) do this for you, but they charge a fee.
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Can't I do this setup of DNS A records in my SME server? Do I have to install another box just to house my BIND DNS Server? I am totally lost!
Yes, all you can do all of this with the public DNS service you have. You do not need to setup another DNS server.
I am not familiar with the web interface for the service you are using, but I'm sure it is similar to the public DNS service I use (easydns.com)
At a minimum, setup an A record to your domain:
A Record 1: domain.xxx = ip address
You can then setup C names, or alias, to your primary A record. For example:
- "www" points to A Record 1;
- "ftp" points to A Record 1;
- "*" points to A Record 1; (wildcard)
You can also setup Mx record to point to your mail server.
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Root_DNS
| Registrar (pem.edu.ph)
| / DNS Server
| / / Other_DNS
| | / /
Internet---Other_DSL---Remote_Users
|
DSL---Your_DSL_DNS
|
SME --Static IP
|
Local_User and Remote_Users
This is my scenario. pem.edu.ph is registered to domain registrar here in the philippines that handles edu.ph domains. In my SME I created 4 subdomains up.pem.edu.ph, au.pem.edu.ph, coc.pem.edu.ph, ui.pem.edu.ph in my SME this four subdomains point to the same static IP address. My question is that will this 4 subdomains be viewable outside of my local network, would it be viewable in the internet. Because each subdomain will be remotely accessed (mail,web,ftp) Thanks
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You have two options:
1. You can make your SME DNS server publically accessible, and then configure your domain at the registrar to use the SME Server as your DNS server. This way when clients ask for the DNS records for pem.edu.ph, they will be using your SME Server as the root for lookups.
2. You can use your registrar to create the same records again, but point all A records to your Static IP. Then when the request hits the SME Server, it will redirect the client to the appropriate ibay and/or server.
I recommend (2) because your registrar probably has a failover in case their primary DNS server goes down.
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ejay69
My question is that will this 4 subdomains be viewable outside of my local network, would it be viewable in the internet.
No
You need to register domain names for them and configure external DNS records for them.
sme server is not a public DNS server.
Just use a free DNS service like zoneedit.com to setup DNS for those domains.
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You have two options:
1. You can make your SME DNS server publically accessible, and then configure your domain at the registrar to use the SME Server as your DNS server. This way when clients ask for the DNS records for pem.edu.ph, they will be using your SME Server as the root for lookups.
2. You can use your registrar to create the same records again, but point all A records to your Static IP. Then when the request hits the SME Server, it will redirect the client to the appropriate ibay and/or server.
I recommend (2) because your registrar probably has a failover in case their primary DNS server goes down.
ejay69
No
You need to register domain names for them and configure external DNS records for them.
sme server is not a public DNS server.
Just use a free DNS service like zoneedit.com to setup DNS for those domains.
Now, which is which this made me more confuse david says yes AND mary says no! I think David's first suggestion would be okay in my case, so pardon me if I have to ask how do I make my SME DNS Server public. Thanks again for your prompt help
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SME Server isn't designed for this scenario, but it can do it AFAIK:
db configuration setprop dnscache access public
signal-event domain-modify
However, Mary is right -- you still need to use your registrar's control panel to register your SME Server as the DNS server for your domain.
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My question is that will this 4 subdomains be viewable outside of my local network, would it be viewable in the internet.
You've already been told that they won't be.
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You've already been told that they won't be.
Ok. understood it won't. SME was not designed for my scenario. One last question and I need one honest answer so that I will know how to pursue another track. So my scenario is not possible for SME Server but will it be possible for other distros (not out of the box distro such as SME)?
Thanks to the SME Community
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Now, which is which this made me more confuse david says yes AND mary says no! I think David's first suggestion would be okay in my case, so pardon me if I have to ask how do I make my SME DNS Server public. Thanks again for your prompt help
Sounds like a step by step HOW TO for setting up multiple domains is in order here.
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Setup domains using the Public DNS system. This is a very basic and simple tutorial and anybody can add or correct as they wish :cool:
1. register the domain. (In my case this is mercyh.org and it is registered at godaddy.com)
2. Point the registrar's records to the DNS hosting servers. (This can be servers that are maintained by the registrar or by another company. In my case the DNS records are hosted on Zoneedit.com servers so I point my registrar records to their server's ip addresses.)
3. On the PUBLIC DNS server (for me Zoneedit's server) create your DNS records. (I of course create an A record for mercyh.org, I also create an alias for www.mercyh.org. both of these records point to my SME server's WAN facing IP address.)
I can create as many alias records as I want
As I own all of mercyh.org and all subdomains I can create subdomain addresses that point to the same or different servers. (I can have a subdomain of payment.mercyh.org that points to a different server)
** I can point as many A records at my SME's external IP address as I wish. These can be primary domains or subdomains.
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On the server above I also host partnersinfamilycare.com. I do not actually control their DNS records. They have simply pointed them to my server's Wan facing IP address using the same procedure outlined above.
On my SME server I simply add the partnersinfamilycare.com domain in the configuration-domains panel in server-manager and point that domain to the Ibay on which their website is hosted. When a request comes in for partnersinfamilycare.com the SME automatically routes it to the correct Ibay and their website is displayed.
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Setup domains using the Public DNS system. This is a very basic and simple tutorial and anybody can add or correct as they wish
Please don't post documentation here. Please ensure that the users manual and wiki and FAQ are complete and accurate. Anything posted here will soon be lost.
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Please don't post documentation here. Please ensure that the users manual and wiki and FAQ are complete and accurate. Anything posted here will soon be lost.
I couldn't agree more.
To me this is basic NON SME dns documentation. I would be fine adding it to our documents but posted it more for the benefit of the OP. I think sites such as dnsstuff.com or any of the many other sites that deal with documentation of how the WWW works are a better place for people to get this information
If anyone has a suggestion where this should be in the FAQ, HOW TO's, etc. I would be glad to add it.
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Someone should really create a DNS howto. I've seen a number of DNS-related queries here over the last little while.
There should be two things: as an FAQ, it should just show how to create the necessary zone records to point to the SME Server for web and email services, i.e.
* A record myserver.mydomain.com
* CNAME record *.mydomain.com > myserver.mydomain.com [catch-all]
* MX record > myserver.mydomain.com
The second thing would be a howto to explain some of the various advanced DNS setups that there can be.
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Added the basic FAQ here:
http://wiki.contribs.org/SME_Server:Documentation:FAQ#External_DNS
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This is what I observed for a people like you guys who are very techy minded...
I admit that I was so amazed by Linux technology and people like me who was a dumb but technology enthusiast wanted to know each and every details of Linux technology but the sad portion was the "SUPPORT"
When we ask a support here in the forum coz we assume that you guys "TECHY PEOPLE" would give us a "INSTANT" procedure/steps/how'tos that the only thing we do is to follow those instructions but what happened?
You give us another link to read!
The reason why we are here to get "INSTANT" information not give us another link for us to do ourselves, I mean we're not like you GUYS...
We're DUMB but curious...
No wonder why so many people like Microsoft and Mac not because of their FANCY APPS and FEATURES but for their HUGE Support for their clients...
I know LINUX si FREE and I agree that before but I realized now that LINUX is only for GEEK...
I don't wanna be GEEK, I just want to KNOW EASY/SIMPLE/STEP-BY-STEP details to follow and I know this is SPOON-FEEDING alike but who will get BENEFIT for these? It's US and we'll use this for other people and for the next generation...
"NOBODY HAS THE MONOPOLY ON GOOD IDEAS, ANYBODY CAN COME UP WITH GOOD IDEAS"
G-d Bless...
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[m364n0]
You have jumped in on a very old post with a whinge, far better you start a new thread with a specific problem or question, having told us concisely what you have done and why it did not not achieve what you wanted etc etc
You seem to think people here have nothing else to do all day but answer questions in a detailed way for your benefit.
We are all busy doing our own lives, but we do choose to contribute a lot of time to help people like yourself, but we can only give so much, and we do expect users to show some degree of "self help" etc.
It is pointless repeating or recreating what has already been published, every time someone asks the same or similar question.
Where existing documentation appears to answer your needs, then you will be referred to it. That's how it is, there is no point writing a new set of instructions where they already exist.
You do need to go away and read what you have been referred to and if you do not understand it or have further queries, then come back with follow up questions.
No one likes a whinger, so show us you have an intent of interest and we will help you as much as our valuable and limited time allows.
Please understand that.