How is it possible to ping a computer name and get reply if not in DNS

I have been assigned an existing project that consists of two domains (Domain A and Domain B) on the same physical network. These two domains do not hat trust relationships and each domain has their own domain controllers and DNS servers, but share a common DHCP server and default gateway.

Domain A was the first domain and Domain B was added later to facilitate a company division that is preparing to separate into a new, independent company.

Some computers on Domain A needed to be accessed by computers on Domain B so the prior admin added a DNS zone to the DNS server in Domain B that listed computer host names and IP addresses from Domain A.

There are no WINS servers running or being referenced on the Domain B domain controller

From the domain controller in Domain B, I can ping the computers listed in that DNS zone by computer name and get a reply, as expected.

However, I can also ping computers in Domain A that are not specifically listed in that DNS zone in Domain B, which makes me think that there must be a link I am missing.

The DNS server in Domain B does not have any forwarders and is just using Root Hints.

I have examined the domain controller in Domain B and it does not have any entries in the local hosts or LMHosts files in the c:\windows\system32\drivers\etc folder

How is it possible that I can ping a non-public computer by name that is not specifically listed in a DNS zone, Host file, LMHosts file or via a forwarder to a Domain A DNS?

Thanks,

Dave
dcadlerAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Rob WilliamsCommented:
NetBIOS and DNS use multiple methods to resolve names such as those you mentioned LMhost, Hosts, DNS, WINS but also simple name caching.  I forget the order, and it varies based on node type,  but when one fails it tries another.  However you cannot count on caching for reliability.
0
JohnBusiness Consultant (Owner)Commented:
Given your conditions, you are better off to access a computer in the other domain. I do that reliably whenever I cannot resolve a name by DNS.
0
Rob WilliamsCommented:
PS-  The following is a good article for a type H (Hybrid) node, the most common, name search order:
http://networkadminkb.com/KB/a118/understanding-dns-client-service-how-name-resolution-works.aspx
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
DrDave242Commented:
It could be a simple NetBIOS broadcast that's resolving that name, since they're all on the same network. Are you pinging just the hostname or the fully qualified domain name?
0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
DNS

From novice to tech pro — start learning today.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.