host or alias?

  • Thread starter Thread starter Jason Gallas
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J

Jason Gallas

When making an alternate name for a server I notice that you can use either
the host or alias. Which is preferred? For example, if I want to name my
mail server 'mail' that has an actual name of 'alpha' I could name it as an
alias or I could just make a host name and use the same IP address. Also,
for a web server 'www' for a server named 'bravo'. Is this the right way of
going about it? If not what consequences could come about by using a host
name (a record) rather than a cname (alias) for both exchange email servers
and other servers?
 
In
Jason Gallas said:
When making an alternate name for a server I notice that you can use
either the host or alias. Which is preferred? For example, if I
want to name my mail server 'mail' that has an actual name of 'alpha'
I could name it as an alias or I could just make a host name and use
the same IP address. Also, for a web server 'www' for a server
named 'bravo'. Is this the right way of going about it? If not what
consequences could come about by using a host name (a record) rather
than a cname (alias) for both exchange email servers and other
servers?
Click to expand...

Not if you are going to have an MX record using these records as the SMTP
server. MX records must point to a mail server host record, never an alias.
 
: In : Jason Gallas <[email protected]> posted a question
: Then Kevin replied below:
: > When making an alternate name for a server I notice that you can use
: > either the host or alias. Which is preferred? For example, if I
: > want to name my mail server 'mail' that has an actual name of 'alpha'
: > I could name it as an alias or I could just make a host name and use
: > the same IP address. Also, for a web server 'www' for a server
: > named 'bravo'. Is this the right way of going about it? If not what
: > consequences could come about by using a host name (a record) rather
: > than a cname (alias) for both exchange email servers and other
: > servers?
:
: Not if you are going to have an MX record using these records as the SMTP
: server. MX records must point to a mail server host record, never an
alias.

So if not using it for an MX record it really does not matter which I use?
 
In
Jason Gallas said:
So if not using it for an MX record it really does not matter which I
use?
Click to expand...

If the name is not used by the MX record, you can use any name, any way you
want that will resolve to the correct IP address.
 
JG> Which is preferred?

There are two sorts of aliases in DNS, server-side and client-side. When one
creates an "alias" in Microsoft's DNS server, one is creating a client-side
alias.

The general rule for client-side aliases is that if there are two ways of
doing something, and only one of them involves the use of client-side aliases,
one should choose the other way.

Usually, one should thus prefer server-side aliases over client-side aliases.
Unfortunately, Microsoft's DNS server is as poor as ISC's BIND is when it
comes to server-side aliasing features. It only supports two sorts of
server-side aliases (some other DNS server softwares support several more),
neither of which have the granularity appropriate to the sort of situation
that you are envisaging.

However, you can always, of course, enter the various names as "hosts" and
perform the necessary "aliasing" manually, keeping the resource records
identical by hand.
 
Give the person a break.
They said
"must point to a mail server host record"
which, taking this to mean an A RR, is correct.
This is even noted in the FAQ
http://intac.com./~cdp/cptd-faq/section6.html#MXCNAMEA
you point out, where it does correctly refer to the RFCs saying
"The letter of the law is that an MX record should point to an A record. "

The poster then appears to fall into the all-to-common
trap of referring to a CNAME RR as an "alias"
Their intent however seems both discernable and correct.
 
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