• We’re currently investigating an issue related to the forum theme and styling that is impacting page layout and visual formatting. The problem has been identified, and we are actively working on a resolution. There is no impact to user data or functionality, this is strictly a front-end display issue. We’ll post an update once the fix has been deployed. Thanks for your patience while we get this sorted.

A few DNS questions

G

Garet Jax

Diamond Member
Hello all,

I am trying to understand DNS a little better so I can hopefully solve a problem on our network.

I am running a Windows 2000 Professional client.

My understanding of how DNS works is the following:
  1. I type "ping <SERVERNAME>"
  1. The OS checks my local cache for a DNS entry mapping the <SERVERNAME> to an IP address
  1. If it finds it locally, then it returns the IP address stored in the cache
  1. If it doesn't find it cached locally, then it will go through the provided DNS servers in the order they are provided
  1. If it still hasn't found it, then it returns an "Unknown host <SERVERNAME>" error
  1. If it finds it on one of the provided DNS servers, then it returns the IP address mapping and caches it locally for the time specified in the TTL setting on the DNS server that provided the mapping

Is this correct?

Also, when I type "ipconfig /displaydns", is this looking at the cache on my local machine or this a cache on the DNS server?

If my understanding above is correct and I type "ping <SERVERNAME>" and the ping resolves it to an IP address, how could my DNS cache (retrieved using "ipconfig /displaydns") still have:

<SERVERNAME>.
------------------------------------------------------
Negative cache entry for no records

as the entry?

Thanks a lot.
 
If ping (or whatever) can't find it locally, it checks the first DNS server you have listed. If that server doesn't have an entry defined locally or in its cache, it sends your request to its upstream partner (usually the ISP that your company or your local ISP uses). If it can't be resolved there, it continues up to the top of the DNS tree. (Network Solutions, or whomever owns them now.) The 2nd, 3rd, etc., DNS entries you have defined on your computer are not queried unless the 1st one you have listed is unavailable.

/displaydns is supposed to show what is cached locally but I don't think it works properly. Looking at mine, I see everything in there are places I've gone but by no means everywhere I've been.

 
bozo1,

Thanks for setting me straight? 🙂

All,

How does WINS fit into the DNS picture? Can someone please explain this to me? Thanks.
 
Actually,
If it's not cached on you machine, then the client requests the info from the DNS sever specified in your TCP settings. The dns server will then query one of the 13 root name servers. The root name servers tell the dns server who is authoritative for the domain in question. Then the dns server asks the authoritative DNS server what the host record is. The autoritative DNS server tells your name server the info, and then you get it. If you want the best dns book out there, you should buy DNS & Bind from O'Reilly. Hope that helps.

Forgot about the WINS question.

WINS is for Microsoft boxes. Basically it acts like DNS for MS machines. It's dynamic, so if you specify a WINS server in your IP stack, your computer will register with that WINS server. Just like a DNS server, the WINS server holds a "database" with hostname and IP of machines. It's a little more complicated, but WINS 2k domains have switched to DNS.
 
Basically it acts like DNS for MS machines. It's dynamic, so if you specify a WINS server in your IP stack, your computer will register with that WINS server. Just like a DNS server, the WINS server holds a "database" with hostname and IP of machines. It's a little more complicated, but WINS 2k domains have switched to DNS.



Part of the reason for DDNS in 2k.
 
You must log in or register to reply here.

TRENDING THREADS

Back
Top