IP Address Allocation Question ?

Question

Hi,

I had a question about IP address allocation when using a Static IP address from your ISP. I have a specific infrastructure in mind.

When you have 1 static IP address from your ISP. How are the other static addresses getting assigned.

I am refering to an infrastructure that has the follwing.

1) Exchange Server - With a Static Address
2) Web Server - With Static Address
3) SQL Server - With Static Address

And of course the domain name corresponding to that IP address.

My question is how are the following 3 IP addresses static when your ISP has also given you a static address. Wouldnt the three above be changing and just the domain IP static? This way it looks like we have purchased 4 static addresses when we have only purchased 1.

Can someone please explain.

Many Thanks in Advance.

Max

Answer 1

When it comes to internet addresses allocated via your ISP, you either get 1, or more, but the setup requires some to be used for 'housekeeping' to provide for broadcast address, etc.



If you have different services (using different ports, eg 25 for incoming mail, 80 / 8080 / others for web pages, 3006 / others for SQL server), then those ports can be forwarded to different servers on your LAN by the router, and they don't need to be given exposure to hackers, or allocated internet addresses, at all.



If you have paid for 4, then ISP is best source of advice.



The domain can have lots of different servers associated with it, as

"A" records (for ftp, mail, etc). It is possible to have all those services (web, mail, sql) going on one server, so you might have



www A 123.123.123.123

ftp A 123.123.123.123

mail A 101.101.101.101

A 123.123.123.123

MX mail.yourdomain.com.



The "blank" name would be for http://yourdomain.com/ pointing to 123.123.123.123 just like www.yourdomain.com and ftp...



The "blank" MX record would accept mail to someone@ yourdomain.com and send it to mail server at 101.101.101.101 (but it could have been the same server as used for your web pages, of course). MX records have additional info (not shown above) to allow for them to be in priority order (ie allows setting of order to try).



I think your last part about the domain IP suggests you are unfamiliar with name servers. You could look on the web for more about Name Servers, and maybe use some of the lookup tools to check existing domains to learn a bit more before contacting your ISP as you don't want them to run rings around you expecting you to know about A records, etc.



One of my clients has a mail server at their office on their ADSL connection. So the name server information has pointers to the web hosting server (which is web space managed by their ISP) and the the first A record for their mail points to their ADSL IP address. There's a second record to a backup mail server in the USA (in case their ADSL goes down).



Good luck!

Answer 2

Your question is kind of hard to follow. Normally, if you pay for a single static address, that one static address is all you get. You can assign other machines local addresses and use NAT to give them Internet access. All outbound connections will appear to come from that one static address. All inbound connections must be made to that one static address.



Normally, when you have an account that permits you to run servers, more than one static address is assigned. Ask your ISP exactly what you purchased from them.



Combinations of static and dynamic addresses are very rare, because they're hard to terminate on the customer end. Most likely, you have one static address and the rest are private addresses (addresses only valid on your network).

Answer 3

If you have only 1 static IP from your ISP, that is the only IP the outside world would see. Which IP's you use interally for your servers is up to you, but preferrably from one of the private IP ranges so it does not interfere with your access to public IP's.



Since the outside world would not see the actual IPs of your servers, if you want access them from the internet, you need a router that can forward specific incoming ports to your private IPs. For example forward tcp port 80 from your public IP to your webserver private IP. Likewise for whatever ports are used for Exchange and SQL. Most simple broadband routers can do that.



Note that if you wanted to use Outlook Web Access to access Exchange, your webserver would likely need to be capable of proxying that, because you can only forward incoming port 80 from on external IP to one internal private IP. With properly configured name based virtual web hosting, you can serve up different content for different names used to access the single webserver. And if properly configured as a proxy, could use a specific hostname to relay info from Exchange.



Note that you can have more than one A record in DNS pointing to the same public IP. In order for mail to work according to RFC's, either the part after the @ in an e-mail address has to be an A record, or you need an MX record that points that to an A record (not a C name).



I actually use a dynamic DNS service (no-ip.com) that points multiple static A names (including wildcard subdomains) at my dynamic public IP.



But everything would be much easier to keep separate if you had a 5 static IP plan.

Answer 4

An IP deal with refers to a unique volume assigned to each and every workstation on the internet. The IP volume is termed an "deal with" because it serves an same objective as a house deal with -- it facilitates each and every device on the internet to be positioned through a numerical scheme An IP deal with has 2 aspects: the identifier of a particular community on the internet and an identifier of the certain gadget (which could be a server or a laptop) interior that community. on the internet itself - it truly is, between the router that flow packets from one element to a unique alongside the direction - only the community component to the deal with is appeared at. There are 4 ip deal with preparation type A addresses are for great networks with many units. type B addresses are for medium-sized networks. type C addresses are for small networks (fewer than 256 units). type D addresses are multicast addresses.