Custom DNS on beta server

[joseph_liu]

hmmmm for some reason its still not working.

I had my webhost create the A record but the page still doesn't come up.

My host told me that fastmail needs to do something to make it work correctly.

Any other thoughts?

Thanks!
Joseph

[BinaryTB]

Wouldn't it be easier to just setup a CNAME record instead of multiple A records? This way if Fastmail ever decides to host their login page from another IP, no changes on your end are required?

e.g.
mail.mydomain.com CNAME www.fastmail.fm

No need for the multiple A records listed in the previous post. Just the MX and the CNAME. This is assuming of course that you have your email hosted at Fastmail (via MX) and only want mail.mydomain.com to go to the login page for Fastmail.

Come to think of it, the easiest way would be just to have a URL redirect for mail.mydomain.com from your webhost to www.fastmail.fm, since I don't know how A records and CNAME records would conflict (if at all) with the SSL certificates that Fastmail uses for its secure login.

[g4mby]

Originally Posted by Spooon69

Wouldn't it be easier to just setup a CNAME record instead of multiple A records?

Easy to set up but it doesn't work, a FastMail error directs users to the main log-in page!

Originally Posted by Spooon69

No need for the multiple A records listed in the previous post.

Really? That's how FastMail have mail.mydomain.com setup and it works for me.

[elvey]

Originally Posted by joseph_liu

Any other thoughts?

Why are you messing with custom DNS at all? Sounds like you would be better of with the recommended standard DNS setup.

[BinaryTB]

Originally Posted by g4mby

Easy to set up but it doesn't work, a FastMail error directs users to the main log-in page!


Really? That's how FastMail have mail.mydomain.com setup and it works for me.

I guess I may have misunderstood the differences between A records and CNAME records. I always thought that A records were to IP addresses what CNAME were to domain names and since domains could resolve to multiple IPs (as www.fastmail.fm does), it could replace A records in some situations.

Anybody have a technical explanation as to why CNAME didn't work in this situation?

[brong]

On the topic of redirection:

I've redone the Websites page to have a single list, separate page to "edit" each website, and a combined creation form that uses some javascript and CSS to hide the irrelevant fields.

I'm hoping this interface will be easier to use and clearer in most cases. I suspect I could add some more sorting options as well if people find that mixing redirections and websites is confusing...

[KenRabbit]

I use another service provider for DNS management, http://www.dyndns.com/ . I can see your DNS service will work for my machines with static IP numbers. However some of the machines I point to, and they are on multiple networks geographically spread, have dynamic IP numbers. This is OK with my current provider as a small application on the machine keeps the DNS records current with the correct IP. Will you be able to support this?

[JasonWard]

Originally Posted by KenRabbit

I use another service provider for DNS management, http://www.dyndns.com/ . I can see your DNS service will work for my machines with static IP numbers. However some of the machines I point to, and they are on multiple networks geographically spread, have dynamic IP numbers. This is OK with my current provider as a small application on the machine keeps the DNS records current with the correct IP. Will you be able to support this?

You can continue to use DynDNS for this (or any of the many other dynamic DNS providers) and then use a CNAME record from your domain to point to the name given to your dynamic IP by DynDNS or whoever.

Jason

[DrStrabismus]

Be careful with CNAMES because they say that the [sub]domain is an alias for the other domain for all DNS. If your domain is example.com it's probably ok to set www.example.com as a CNAME for a dyndns hostname, but don't set example.com itself this way unless you want your MX records set at dyndns too.


Using a CNAME at namecheap to access my webspace works for me

[JasonWard]

Originally Posted by DrStrabismus

If your domain is example.com it's probably ok to set www.example.com as a CNAME for a dyndns hostname, but don't set example.com itself this way unless you want your MX records set at dyndns too.

MX records should never resolve to a name that resolves to a CNAME, it is against the RFC's (rules) and some mail programs may "correctly" fail to send email to domains where the MX domain lookup doesn't result in an A record.

However, there is no reason why your mail server for example.com should be on example.com, none at all, indeed for users of Fastmail your mail server is probably in1.smtp.messagingengine.com and in2.smtp.messagingengine.com if you are running your own mailserver either setup mail.example.com and give that an A record or if you are wanting to resolve to a dynamic IP just point the MX record directly to the name given to it by your dynamic dns provider.

So your DNS could look a bit like this

example.com     CNAME me_at.dyndns.org
www.example.com CNAME me_at.dyndns.org
example.com     MX    me_at.dyndns.org

Note I've deliberately missed the time to live (TTL) and MX priorities from the example. However other than that, the above is a perfectly correct DNS for the domain example.com

If you Google around for information on DNS you will find some articles that say "don't use a CNAME for your www record" and others that say "don't use a CNAME for your main domain." The reason they say this is not because there is anything against the rules to doing that, but because it causes the client to do more DNS lookups each time it needs to resolve the name, which results in slower lookup times for them and heavier loading on the DNS server.

So on balance if you are able to sensibly avoid using CNAME records, avoid them, however if you are not, then don't worry about it.

Jason

[brong]

Originally Posted by JasonWard

MX records should never resolve to a name that resolves to a CNAME, it is against the RFC's (rules) and some mail programs may "correctly" fail to send email to domains where the MX domain lookup doesn't result in an A record.

However, there is no reason why your mail server for example.com should be on example.com, none at all, indeed for users of Fastmail your mail server is probably in1.smtp.messagingengine.com and in2.smtp.messagingengine.com if you are running your own mailserver either setup mail.example.com and give that an A record or if you are wanting to resolve to a dynamic IP just point the MX record directly to the name given to it by your dynamic dns provider.

So your DNS could look a bit like this

example.com     CNAME me_at.dyndns.org
www.example.com CNAME me_at.dyndns.org
example.com     MX    me_at.dyndns.org

Note I've deliberately missed the time to live (TTL) and MX priorities from the example. However other than that, the above is a perfectly correct DNS for the domain example.com

If you Google around for information on DNS you will find some articles that say "don't use a CNAME for your www record" and others that say "don't use a CNAME for your main domain." The reason they say this is not because there is anything against the rules to doing that, but because it causes the client to do more DNS lookups each time it needs to resolve the name, which results in slower lookup times for them and heavier loading on the DNS server.

So on balance if you are able to sensibly avoid using CNAME records, avoid them, however if you are not, then don't worry about it.

Jason

That and every MTA in existance will rewrite your email from:

foobar@example.com to foobar@me_at.dyndns.org, completely ignore the "MX" record above and deliver to the MX record for me_at.dyndns.org and, um - steal your lunch.

Seriously.

We rolled out a change that used CNAME records for our domains once. For about 12 hours. We had a zillion emails to username@web.messagingengine.com. Some clients had even rewritten mentions to the old address in the body of the email when they quoted because they were online and they could do an MX lookup.

Yeah.

Just don't do it if you're using the domain for email.

[JasonWard]

Originally Posted by brong

That and every MTA in existance will rewrite your email from:

foobar@example.com to foobar@me_at.dyndns.org, completely ignore the "MX" record above and deliver to the MX record for me_at.dyndns.org and, um - steal your lunch.

So, before looking up the MX record of the domain, the MTA's lookup the domain itself, and if it's a CNAME substitute the CNAME for the actual domain?

Your kidding? Is this just practice or is their an RFC that says MTA's should so that?

We rolled out a change that used CNAME records for our domains once. For about 12 hours. We had a zillion emails to username@web.messagingengine.com. Some clients had even rewritten mentions to the old address in the body of the email when they quoted because they were online and they could do an MX lookup.

Yeah.

Just don't do it if you're using the domain for email.

Gulp...

So, to get full control of a domain that resolves to a dynamic IP you actually need full control of DNS for the subdomain (me_at.example.com in the examples)?

So you would need

example.com     CNAME me_at.dyndns.org
www.example.com CNAME me_at.dyndns.org
example.com     MX    me_at.dyndns.org

and

me_at.dyndns.org     MX    me_at.dyndns.org

But even then expect your email address to be rewritten.

It would appear the only way to solve this would be to point example.com as an A record at something that does a web redirect to www.example.com.

I wonder if any of the dynamic DNS providers allow you to set DNS for your dynamic address?

Perhaps a hole in the market Fastmail might want to plug?

Jason

[DrStrabismus]

Irrespective of any email address rewriting, the line

example.com CNAME me_at.dyndns.org

means treat example.com as another name for me_at.dyndns.org. So when looking up *any* record at example.com's nameservers you should get a cname instead, and have to perform a lookup with me_at.dyndns.org instead.

Setting a cname for www.example.com is OK, unless you use addresses like fred@www.example.com. Addresses at example.com itself will then use an ordinary MX lookup.

[brong]

Originally Posted by DrStrabismus

Irrespective of any email address rewriting, the line

example.com CNAME me_at.dyndns.org

means treat example.com as another name for me_at.dyndns.org. So when looking up *any* record at example.com's nameservers you should get a cname instead, and have to perform a lookup with me_at.dyndns.org instead.

Setting a cname for www.example.com is OK, unless you use addresses like fred@www.example.com. Addresses at example.com itself will then use an ordinary MX lookup.

Yes, true. www.example.com is fine as a CNAME (often www.example.com. CNAME example.com. in fact!)

Bron.

[ao1]

Originally Posted by robmueller

For people with domains pointing to our name servers (ns1.messagingengine.com and ns2.messagingengine.com) you can now change the DNS generated by our nameservers for your domain.

Am I right to understand that this feature is only for "enhanced" users?