DNS cache only and secondary zone

Can some explain the difference between DNS cache only and secondary zone
If I understand, when you configure  DNS as Root Hints only, It queries and caches Internet DNS names to IP resolution.
But if you want to cache Names to IP address resolution for an Internal DNS located in a remote site that has slow link. How do you configure caching.?

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Depends what you want, a secondary zone will download ALL the records in that zone regardless if the remote site will use all those records, so if your zone is quite big (500 records at your HQ) vs 10 clients at your remote site it may not be a good use of bandwidth.

A caching only server will cache only the records that go thru the DNS server which have been requested by clients so it can be more efficient.

To setup a caching only server normally you would just install DNS and it would cache all records for the internet, in your case if its a remote site to cache internal records you would go to your DNS server properties, go to forwarders add your DNS domain (e.g. domain.local) and then point it to your main DNS server IP address.
This will mean any DNS queries for that domain will be resolved via your main DNS server and the remote server will cache all the records requested which can be quite efficient.
Also instead of using root hints you can setup a forwarder for all other domains to point to your ISP DNS which can be faster.

Hope this helps
jskfanAuthor Commented:
would secondary zone transfer the whole zone each time or just the changes. if it's just the changes, I believe it's better creatng a secondary zone than delegating the zone or using forwarder. correct?
Chris DentPowerShell DeveloperCommented:

> each time or just the changes.

Generally just the changes. Provided it supports Incremental Zone Transfers (IXFR), modern DNS servers do. In which case it will get a list of added records, and a list of removed records.

Bear in mind that to Transfer a zone you need permission (granted by the holder of the zone). You couldn't transfer google.com for example.

Essentially, a Secondary Zone is faster, all data is local, but it carries a much higher administrative overhead as the transfer must be properly managed and monitored.

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Damn I had replied to this no idea what happened, but yes win server 2000 upwards would definitely be incremental transfers and once its setup it should be fine.
jskfanAuthor Commented:
you 'll still get credit for it.........lol....
jskfanAuthor Commented:
I guess I am mixing up things...

Secondary is used for a different purpose than Delegation or stub zone.
Secondary is the same zone as the primary, and it's used if you have clients accessing the same zone in 2 different sites.
Delegation is used if you have a parent and sub zone and want clients from parent to query for a host in the sub zone.
stub zone is the same as delegation, it just has the feature of updating the NS records automatically if there is change to it in the authoritative server.

SO...can we just use stub and forgot about the Delegation?
when you delegate the sub zone from the parent zone or create a stub zone which DNS server is authoritative, is it the one on the sub zone?

Chris DentPowerShell DeveloperCommented:

> stub zone is the same as delegation


Stub Zones don't require ownership of the Parent. Stub Zones are most like Conditional Forwarders except one updates dynamically (Stub) and the other doesn't (Forwarder).

> SO...can we just use stub and forgot about the Delegation?

It depends on what you're trying to achieve. It would be foolish to build a DNS hierarchy based on Stub Zones in my opinion.

> which DNS server is authoritative

All name servers (as listed in the NS records) for the domain in question.

Thanks jskfan, I'm trying to get 10000 points to become a full member ;)

Stub Zone you are correct that it will update automatically the NS records.

When you Delegate, e.g. sub.company.local the queries for sub would go to whatever dns server you delegated it to, the primary server will not have the all the A records for it so it cant be considered authoritative as it doesn't have knowledge of all hosts.
If you use a stub zone it will be similar to conditional forwarding as I Described as it will not have any Host records stored, only the NS records which will point it to the DNS servers at your primary/HQ site so it will cache any queries going thru it.

If you want all queries resolved locally at your remote site for all the host records then secondary zone is what you want as it will copy ALL records off your main server.

So the question is, how many of the queries at your remote site will be for IP addressed located in your main site.. if its not that many then stub zone will be fine as it can cache only the queries your hosts will actually use and not all of them , hope that makes sense :)
jskfanAuthor Commented:
If I understood the difference between conditional Forwarding,Delegation,Stub:
1-Stub zone vs Delegation
- stub zone:can query any DNS in the world
- Delegation has to follow the name space of the parent zone.
2-Stub zone Vs Conditional forwarding
stub zone: the DNS server in the parent zone looks for other DNS servers in order to resolve the query.
Conditional forwarding: the DNS stated in the forwarding will look for other DNS servers to resolve the query.
3-Delegation Vs Conditional forwarding
- Delegation has to follow the name space of the parent zone.
Conditional forwarding:can query any DNS in the world

-you can configure conditional forwarding and stub zones of your queries to any DNS server in the world.
-stub zone
That sounds right except

"2-Stub zone Vs Conditional forwarding
stub zone: the DNS server in the parent zone looks for other DNS servers in order to resolve the query."

In conditional forwarding you have something for "all other domains", the stub zone will only be queried if the query is for that stub zone, otherwise it will use the dns entry in "all other domains"

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Chris DentPowerShell DeveloperCommented:


Stub Zone - Must reference a server which is authoritative for the zone. The referenced servers must be able to provide a direct answer.

For example, you couldn't create google.com as a Stub Zone and point it at anything other than the Name Servers for google.com.

Conditional Forwarder - Can reference a third DNS Server. Only needs to reference a server which knows the way (as long as that server is willing to execute the forwarded query).

For example, you could create a conditional forwarder for google.com and send it to any other DNS server to resolve.

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