A few easy (for an expert) questions about DNS, load balanced IPs, and IP numbers
Posted on 2008-06-20
I am trying to understand the ins and outs of DNS, which is necessary but very hard given my primary role as a developer and the complexity of what I'm trying to set up. My main use for DNS will be to serve redundant website and web application needs rather than clients connecting on an internal network. I have a few questions about DNS as its relates to use with IIS and NLB.
Background: My server's network card has two IPs assigned to it: if you go to TCP/IP settings for the device, you can see two IPs listed. For the first IP, I have set up my own nameserver at my domain name provider and it points to the IP of my server. For the second IP, our institution is providing institution.edu and my DNS is a subdomain of that: ourdomain.institution.edu. I My IIS websites are set up to keep an eye out for both IPs. One of these IPs I eventually intend to set up as the IP for an NLB cluster.
Question #1: In DNS, in my ourdomain.institution.edu.local folder of my forward lookup zones, BOTH of the IPs mentioned in the previous paragraph have Host (A) records. Is this correct or not? Will this be correct once my clustered IP is set up?
Question #2: What does the ourdomain.institution.edu.local section refer to? Perhaps the local (private) network? This is a basic question about DNS.
Question #3: What does the _msdcs.ourdomain.institution.edu records refer to/mediate? This is a basic question about DNS.
Question #4: Again in the forward lookup zones, I have nameserver records that include BOTH IPs described in the paragraph above in the following sections:
I am wondering if both IPs should be listed in the nameserver records in all of the places listed above, especially myCustomDomainNameBeingPointedFromMyDomainNameProvider.com.
Question #5: for redundancy on the name resolution on my websites, I will want to have multiple nameserver entries on the SOA record, correct? This does NOT mean that I want multiple Host(A) records mapping to each of my servers' IPs, unless I have a site set up on each IP, correct? My understanding is that when I finish getting my NLB clustering set up for my IIS websites, in the forward lookup zone associated with a particular website, I should remove the (A) record that corresponds to an individual server IP and only put the cluster IP in place, as an A record, correct or no? If not what is the right practice?
Question #6: If I right click on the "interfaces" section of my DNS server, I see "Listen only on the following IP addresses". Two are listed as described in my intro paragraph. Should I be listening on all IP addresses? What is the advantage and tradeoff?
Question #7: I understand there is a limit on the use of host header mapping when you are trying to host https-secure websites. What is that limit, generally?
Question #8: My SOA and nameserver records refer to ourdomain.institution.edu.LOCAL [emphasis mine]as the name servers, for both seemingly internal uses (the ourdomain.institution.edu.local and _msdcs.ourdomain.institution.edu sections), and for external uses (e.g. forward lookup zones corresponding to names corresponding to websites. I am wondering if this is perfectly acceptable or not. Both names will resolve from inside the network, I think (.local and non-.local); why use one or the other for this need?
Many thanks for any insights you can offer. I'm finding the whole DNS thing rather difficult, but am slowly but surely learning some of the things I need to know.