It's a bit of an alphabet soup to get your head around isnt it?
This is a pretty good guide
http://www.google.com/support/a/bin/...n&answer=48090

If I have this right, every world wide website must have:

NS Record (2 actually),

and at least one A Record (but usually at least 2, http://example.com and http://www.example.com),

and usually an MX Record (but not necessarily, not all domains have email),

Occasionally there are one or more CName Records (subdomain)

and DNS is the global set of A Records, MX Records and CName together.


Is that correct?

Ignore my post.

Yes you have it correct

and at least one A Record (but usually at least 2, http://example.com and http://www.example.com),

Nope, you only need ONE 'A' record to point the hostname to the IP, the www sub can be an alias (CNAME)

Occasionally there are one or more CName Records (subdomain)

Not necessarily.
I use a cname record for my devs sites against the A record. That way, they stay in sync.
You can basically use a cname for anything you would have used an A for.

So a CName record is everything that comes in front of example.com?

For example:

www.

www.subdomain.

are both CName records?

Not necessarily.

A 'CNAME' is an alias to an 'A' record, but subdomains could be set as an 'A' record.

Originally Posted by chrishirst

Not necessarily.

A 'CNAME' is an alias to an 'A' record, but subdomains could be set as an 'A' record.

You are making my brain ache.

So if a subdomain is set as an 'A' record it wouldn't need a CNAME record?

It would also mean that

http://subdomain.example.com

works but

http://example.com

would return "Server not found" in the browser?

Correct?

Quite possibly.

EVERY entry for any given hostname could be an 'A' record. However this would make modifications "cumbersome"

example.com			A	nnn.nnn.nnn.nnn
subdomain.example.com		A	nnn.nnn.nnn.nnn
mail.example.com		A	nnn.nnn.nnn.nnn

Originally Posted by chrishirst

Quite possibly.

EVERY entry for any given hostname could be an 'A' record. However this would make modifications "cumbersome"

example.com            A    nnn.nnn.nnn.nnn
subdomain.example.com        A    nnn.nnn.nnn.nnn
mail.example.com        A    nnn.nnn.nnn.nnn

As Chris says,

So, you can see if you had
moo.example.com
test.example.com
etc
etc
etc
etc
all as A records and all pointing to the same ip that the A record for example.com is.

To save time if you update your ip, you would have
moo.example.com as a cname for example.com

then all you do is update the (1) A record for example.com
this owuld then update every other cname at the same time.

Thus no need to update 100's of A records.

Time to dig up an old thread with a new question.

I have a client who needs to move to a new web host.

Hypothetically, could he keep all his email accounts going on the existing
account and just move his web site by changing the A record on his existing site?
(in effect paying for two hosting accounts - not ideal but is it even possible?).

Usually with a domain registrar we can only edit settings at the DNS level can't we? i.e. at the domain registrar level it is impossible to have A records and MX record pointing to different hosting locations. Is that correct?

Hypothetically, could he keep all his email accounts going on the existing
account and just move his web site by changing the A record on his existing site?
(in effect paying for two hosting accounts - not ideal but is it even possible?).

Yes it's possible. I use that myself.
My sites are hosted at one place, and my emails are managed by google, thus an MX record poiting to another location than the A records.

Usually with a domain registrar we can only edit settings at the DNS level can't we? i.e. at the domain registrar level it is impossible to have A records and MX record pointing to different hosting locations. Is that correct?

This is highly related to the system, and the interface, the registrar gives you to make your changes.
I use separate entity to register domains and to host them.
Specifically, I use Hexonet for registering and managing DNS, and a small local datacenter with a vps to the hosting.
In the managing area from Hexonet, I have total control over every entry in my
dns zones.

Originally Posted by tripy

Yes it's possible. I use that myself.
My sites are hosted at one place, and my emails are managed by google, thus an MX record poiting to another location than the A records.


This is highly related to the system, and the interface, the registrar gives you to make your changes.
I use separate entity to register domains and to host them.
Specifically, I use Hexonet for registering and managing DNS, and a small local datacenter with a vps to the hosting.
In the managing area from Hexonet, I have total control over every entry in my
dns zones.

Thanks mate. That was very well explained.

good thread, cleared some details for me, tnx

Thanks mate. That was very well explained.

I believe you always can get in touch with web hosting provider and ask for the help. I believe they will not regret helping you