any consequence if use vCenter's hosts entries 1st during ESXi hosts setup & later create DNS FQDN entry record

sunhux
sunhux used Ask the Experts™
on
My vendors are here setting up 5x ESXi hosts for me but they just
requested for FQDN (fully qualified domain names) to be registered
first for these 5 ESXi hosts in the DNS.

However, it will take 2 weeks for the Change Request to be approved
 to create the 5 servers' DNS entries / records.

In the meanwhile, to get the job started, can I just define these 5
servers in the vCenter (or vSphere's ) hosts file first, & once the
DNS entries have been created, we'll remove from hosts file?

I was told by vendor that using hosts file may cause intermittent
instability & corrupt the vCentre subsequently & may require the
whole vCentre to be reinstalled.  Vendor said he has also seen
the ESXi hosts may face intermittent disconnects from LAN/storage
when we migrate from hosts to DNS subsequently.  They said it's
best practice to start with FQDN using DNS entries from the start
& not switch from hosts to DNS.  Are these claims true ??
We're using Windows 2000/2008 DNS
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Commented:
As long as you define the entries correctly in the vCentre Server, all hosts and any PC which will run the VI client it will work fine.. Of course you should remove these entries after the DNS records are created
Commented:
Possibly the vendor is over stating the situation.. BUT you do need to create the entries correctly and be sure to test them to confirm everythings working correctly..
Enable SSH on the ESX hosts and use WinSCP to connect to them. from there you can simply browse to the /etc/host file to add the host entries
Sr Windchill Consultant
Commented:
It is funny that the vendor would say using host entries could be intermittent, when in fact the only thing that would do that is a shoddy dns server with network issues, the host file is local.  That is why they saw issues AFTER migrating off using host file, because that particular setup must have had a bad dns setup in the first place, causing them not to use it at first.

In the end though, do you have to trust him for support on this?  Will he continue to support it if you do it your way?

I would use the host file in your situation, but he is right about best practice, you probably should have had the FQDN change request ready.
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Paul SolovyovskySenior IT Advisor
Top Expert 2008
Commented:
In previous versions FQDN was critical for HA operations but for vSphere 5.0 the HA software has been recreated from scratch and doesn't use FQDN entries.  This was case with most DNS issues from ESX 3 to ESX 4.1.
Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
Fellow 2018
Expert of the Year 2017
Commented:
Yes, as a workaround this will work okay with no issues.

Many sites, implement this practice anyway, to stop DNS traffic!

Just make sure the FQDN are the same and static!

e.g. FQDN match the correct IP address.

Author

Commented:
Honestly, I have quite a lengthy debate with this 'preferred' vendor:
I being ESXi/VMware illiterate (but I know from the days I support
Solaris, I've created local entries in /etc/hosts & later moved on to
use DNS entries after removing /etc/hosts), I did not face any issue.


>In previous versions FQDN was critical for HA operations but for vSphere 5.0 the HA
>software has been recreated from scratch and doesn't use FQDN entries.  This was
>case with most DNS issues from ESX 3 to ESX 4.1
I suppose the vendor ran into the above issue with HA & DRS failover
& possibly anti-affinity rules?  So can I safely say for vSphere 5.0, if I
use hosts entries in vCenter 1st & when the Change Request is
approved 10 days later, I can safely replace them with DNS entries??

The 2 vendor engrs are VCP & they retorted that I'm no VCP.

Q3:
one more question:
if I don't use VLAN tagging currently but at a later stage enabled
VLAN tagging, is this just a small effort or it involves a major
effort (like reinstalling the entire ESXi ? )
Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
Fellow 2018
Expert of the Year 2017
Commented:
DNS is recommended, but hosts file will work. DNS and Gateway's is possible one of the failures for HA!

VLANs
It's easy, just needs physical switch configuration changing and new virtual port groups created.

Have a look here

Pages 13 - 73 Discuss Networking in Detail, iuncluding trunks, VLANs, switches, and load balancing

ESXi Configuration Guide ESXi 4.1
http://www.vmware.com/pdf/vsphere4/r41/vsp_41_esxi_server_config.pdf

Virtual Networking
http://www.vmware.com/technical-resources/virtual-networking/virtual-networks.html

Virtual Networking Concepts
http://www.vmware.com/files/pdf/virtual_networking_concepts.pdf

http://en.wikipedia.org/wiki/Virtual_LAN

http://en.wikipedia.org/wiki/IEEE_802.1Q
Sample configuration of virtual switch VLAN tagging (VST Mode)

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1004074

http://blog.scottlowe.org/2006/04/17/vlans-and-port-groups/

How to Setup VLANs

http://www.vladan.fr/great-kb-on-how-to-configure-vlans-on-vswitches-pswitches-and-vms/

VMware ESX Server 3: 802.1Q VLAN Solutions

http://www.vmware.com/pdf/esx3_vlan_wp.pdf
http://kb.vmware.com/kb/1004127
http://kb.vmware.com/kb/1004074
http://kb.vmware.com/kb/1004252

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