Making sense of DNS and Dynamic DNS?

Discussion in 'Home Networking' started by Tony, Jan 30, 2005.

  1. Tony

    Tony Guest

    I would just like to ask a question on the use of DNS, and my likelihood of
    being able to make use of the service if I signed up...

    Let me put you in the picture. I have had a .com domian now for a few
    years, and although I have been offered DNS Management as an optional extra
    on my domain, I have never signed up to it. The problem is, I don't realy
    know if it would be of any use to me. I have read the information on their
    website regarding DNS, and they say that using it, I can direct a URL, for
    example '' to an IP address of a computer.

    Now my problem is, I have not got a fixed IP address and so everytime I lose
    my connection, the IP address changes.

    Because I have 'server assigned IP' I have been using No-IP for dynamic DNS
    for a couple of year, to allow my computer to be located on the net.

    My question is, if I sign up for DNS Management with my domain provider
    (namezero), will I then be able to stop using No-IP, and rely entirely on
    the service of namezero, or would I be better off carrying on using No-IP?

    The namezero website, sort of suggests that I have to point to a IP address
    manually, which would be a major problem if it wasn't updated automatically
    when I lost a connection, as I would have to log into them everytime to
    update the system with my new IP address...

    My end aim is to set up my own mail server using my domain name, but I'm a
    bit confused about the best way to do it.

    NO-IP Dynamic DNS service has been excellent up to now and if required I
    would upgrade from the free account I currently use, to a more powerful
    option by paying a yearly fee, if it was going to benefit me with what I
    want to do.

    I would appreciate any help you might be able to offer on this...

    Best Regards

    Tony, Jan 30, 2005
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  2. Tony

    Alex Fraser Guest

    No-IP (and others offering similar services) are, as you'd expect,
    specifically geared up for people in your position. As you mentioned, there
    is software to update their DNS servers automatically - you probably won't
    get that with your domain provider's DNS management.
    Running your own mail server is not trivial - you really have to make sure
    you understand how the server is configured, else you are likely to be
    providing an open invitation to spammers. Which is a Bad Thing(tm).

    Running a mail server on a dynamic address is possible but less preferable
    than doing so with a static address. The problem - small but unavoidable -
    is that whenever your address changes there is a window where new mail could
    be scooped up by someone else.

    Mail routing is controlled by MX records, which specify a name (*not* an
    address) to forward mail to. If you want to run a mail server for, you could use namezero's DNS management to add an MX record
    for of "" (or whatever it is), and run
    the No-IP dynamic update client to keep the address associated with up to date.

    Alex Fraser, Jan 30, 2005
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  3. Another problem is that quite a few mail exchanges will not accept mail
    from dynamic addresses - there are blacklists for them similar to the
    known open relay blacklists.

    The reasoning is that a lot of viruses attempt to send mail directly, and
    by blocking mail from dynamic addresses, much undesirable traffic can be
    stopped. Virtually all ISPs provide "smart hosts" for their customers to
    relay mail through, so it can be argued that it is never necessary to send
    mail from a dynamic address.

    So if you try to do this, you will probably find a fair proportion of your
    mail getting rejected.

    Regards, Ian
    Ian Northeast, Jan 30, 2005
  4. We are talking about receiving mail in not sending mail out? The OP
    could always use a smart host for sending mail out, even though they
    receive their mail direct to the box via the sender's MTA.

    Andrew Hodgson, Feb 5, 2005
  5. Yes that is right, however I would say at this point that there are a
    lot of good registration providers out there, a lot now providing this
    sort of functionalities by default/no extra cost.
    If Namezero don't specify dynamic DNS then it won't be a good idea to
    go with the namezero service. One thing you could do is to create
    some DNS records in your namezero domain to point to the name of the domain you own. This can be done easily with MX (mail
    server) records, but if you want to do this with any other record
    type, it won't work, and you would have to use a cname record, which
    will cause the system to look up the IP of the pointed to record.

    For example: has 2 MX records, the first going to, and a second provided by a backup server (for
    when your server is offline). has a cname pointing to

    There are posts on this topic regarding issues running mail servers
    with a dynamic IP.
    Or use cname/MX records in the way I showed you above, however, read
    You really need to get to grips with this before you start moving your
    domain over to the new server, why not set up a mail server
    temporairly for
    Yes, that is the way I would probably go. No-ip can either host the
    domain for you entirely, or you can just run the DNS for your domain
    from no-ip. In the Namezero control panel, there will be a section to
    enable/disable DNS management, and also to have the nameservers
    delegated to another set of servers, which would be the
    servers. You would then do all the DNS management (including dynamic
    DNS on your domain) through

    Andrew Hodgson, Feb 5, 2005
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