Andrew N. Kowtalo
asked on
DNS fails on first try
Hey Gents, have a serious issue
On DNS and DC servers NSLOOKUP's fail on first attempt. However on second attempt addresses resolve.
Users are experiencing the same issue hitting websites.
Any ideas on why its failing on first attempt.
On DNS and DC servers NSLOOKUP's fail on first attempt. However on second attempt addresses resolve.
Users are experiencing the same issue hitting websites.
Any ideas on why its failing on first attempt.
ASKER
Hi Paul,
What do you mean by multi-homed ?
There is three local DNS servers
clients have two dns servers defined in there DHCP scope.
When clients switched to 8.8.8.8 dns everything worked.
What do you mean by multi-homed ?
There is three local DNS servers
clients have two dns servers defined in there DHCP scope.
When clients switched to 8.8.8.8 dns everything worked.
There is three local DNS servers ….. When clients switched to 8.8.8.8 DNS everything worked.
Why 3? The above suggests one or more of the DNS servers is out of date or out of sync with the others.
Can you get by with one?
Why 3? The above suggests one or more of the DNS servers is out of date or out of sync with the others.
Can you get by with one?
ASKER
@John We are replacing a SBS with Server 2016. Right now there are 3 but with SBS removed there will be 2. 1 main and 1 failover. They will both be Server 2016.
Tip: Debugging DNS can be... tricky...
If 8.8.8.8 works, then try setting up the following DNS servers...
This set of servers will provide very fast lookups.
As John suggested, if you have intermittent failures, this suggests a mismatch of DNS records, which can cause instability + tends to be difficult to debug... unless you debug this type of problem on a daily basis...
To debug...
1) Find all your NS records.
2) Do a lookup against each separate NS record for some other record.
3) When you have a lookup mismatch, then you know the problem NS server.
And if faster resolution is required, just setup a local caching server, which uses the above list of servers.
If 8.8.8.8 works, then try setting up the following DNS servers...
8.8.8.8
8.8.4.4
1.1.1.1This set of servers will provide very fast lookups.
As John suggested, if you have intermittent failures, this suggests a mismatch of DNS records, which can cause instability + tends to be difficult to debug... unless you debug this type of problem on a daily basis...
To debug...
1) Find all your NS records.
2) Do a lookup against each separate NS record for some other record.
3) When you have a lookup mismatch, then you know the problem NS server.
And if faster resolution is required, just setup a local caching server, which uses the above list of servers.
Does the first attempt fail even when trying to resolve a local name, or only when trying to resolve something external? Can you post a screenshot of nslookup output showing the issue?
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ASKER
Great work gents.
ASKER
@DrDave it was failing by external names. They did try internal but now its working.
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Is DNS available on the local network, or do clients have to query a remote server?
Do clients have more than one DNS server defined for their use?