DNS to IP Resolution

[Fletch12]

I noticed a problem with the WMI tool when it's resolving names on our network. So I started out with troubleshooting via ping. To keep it simple, for some reason when I try and ping a computer by its name... "ping computerA", I get a reply back even though that computer is not connected to the network (but it was a one point). The IP address I get in reply is 10.20.30.40. So then when I try and ping that IP address with a "-a" option... "ping -a 10.20.30.40", I get a different computer name, such as "computerB". Is there a cache in the DNS or DHCP server I need to clear?

 

[Serbtastic]

Run the following commands and post the outputs for analysis:

nslookup computerA
nslookup 10.20.30.40
nslookup computerB

This will tell us what is defined on your DNS server.

 

[Fletch12]

[COLOR=red yellow]nslookup computerA[/color]
Server: dc.domain.com
Address: 10.10.10.10

Name: computerA.domain.com
Address: 10.20.30.40
[COLOR=red yellow]nslookup 10.20.30.40[/color]
Server: dc.domain.com
Address: 10.10.10.10

Name: computerB.domain.com
Address: 10.20.30.40
[COLOR=red yellow]nslookup computerB[/color]
Server: dc.domain.com
Address: 10.10.10.10

Name: computerB.domain.com
Address: 10.20.30.40

 

[Serbtastic]

You'll need to remove the A record for computerA (with IP 10.20.30.40) on your DNS server.

 

[Fletch12]

I will remove this record but is there a problem with the setup that would be causing this? Should there be only 1 host name per Host IP Address for each pointer? Thanks for the help.

 

[pbunyon]

Not sure of the tool your utilizing but I do a couple things about dns/ip/dhcp issues.
1. Is there a cache in the DNS or DHCP server I need to clear? I know you have a cache on your local box and you can clear this via the ipconfig /flushdns from a command prompt. The ipconfig command was provided for earlier versions of Windows, the /flushdns option is only available for use on computers running Windows 2000, Windows XP, or Windows Server 2003 operating systems.
Regarding the DNS & DHCP servers were the actual changes/assignments are made, these server replicate with others in the environment and generally dns/dhcp updates can be active as short as seconds or as long as 30 minutes. It really depends on the size of the enterprise and how the servers have been set up for replicating. I know personally when making assignment via QIP (Lucent) & CNR (Cisco), that upon assignment it was a requirement to refresh the server to force assignments.

2. Should there be only 1 host name per Host IP Address for each pointer? Yes, only one arecord per IP, although you can have several cnames/alias's (pointers)to the same IP. Unlike lower layer communication, a unique fqdn must exsist for TCP/IP communication.
In the case you have above either computer A or B would gain access depending on which computer logged in first. The other would recieve an error message referring to duplicate IP.

Just food for thought. Don't want to step on any toe's but I ran across this post and hadn't seen a reply from Serb

[blue]Mahalo[/blue]

Paul