pantscat

Run DCDIAG from a command prompt on all your DCs - this should highlight any issues.

DHCP can sit on any box at all. Doesn't have to be on a DC. I suspect there are some name resolution issues at work here.

What colour is the fibre? It's most likely going to be multimode...

Well, if a DC is switched off it won't be able to process requests, BUT, it'll still be listed in DNS as an "available" DC. When clients come to do group policy processing they may try to contact the switched off DC, since it's in DNS, and fail to process anything as they can't contact it because it's switched off. This is entirely normal behaviour if you just switch a DC off. They're not meant to be turned off.

It's definitely DNS. I'll eat my hat if it's not.

Is DNS working ok on the new servers? Replicating properly and answering nslookup requests?

As above - are all your clients pointing to the new DNS Servers? Do you use DHCP for all your clients? It's not possible that some of them have fixed IPs or fixed DNS? Have you demoted the old DCs? or just switched them off?

An old Lenovo X201 i5, with 4GB RAM and a 256GB SSD... does the job!

I've used XMA in the past and they've been fine as a box shifter. The Viglen hardware offers good value, but they aren't as well built as HP or Lenovo boxes.

Will it boot from an OS on an external disk? That will rule out dodgy RAM...

Yes, perhaps I over simplified it a tad - LACP trunks would make a difference, as would contention ratios.

If they're old and out of warranty then that is a reasonable enough reason. If it's a 1gig link then there's little point in having 1gig to the desktop, unless you're planning on upgrading to 10gig at any point.

What speed is the link from the core to the edge? What are you trying to achieve? better performance? Newer kit for warranty purposes? Easier management?

I used to use the 5412 and 5406zl. The 2920s are pretty decent for edge switches too.

The HP 5400 series are really solid core switches - I'd definitely recommend these. For the edge, it really depends on what features you need. Do you use PoE? VoIP? Anything like 802.1x auth?

What grant is this? Sounds intriguing...

Veeam is licensed per CPU socket.

Or PowerShell, the GUI for Exchange 2010 wasn't really finished... and wait 'til you see 2013... it's genuinely easier to do most things from PowerShell then.

Yep, it does - http://exchangeserverpro.com/exchange-2010-send-as-permissions-distribution-group/ Guide On How To Allow Users To Send As Distribution Group Guide - Techieshelp.com

Are you using Exchange? If so - set the secondary email address to be a distribution group (with the Head as a member) and then set SendAs permissions on the distribution group and use the "From" field in Outlook to select that as the reply address.

Another vote here for EOP and using Spamhaus... worked wonderfully when I used it.

Tough lesson that one! Oh well! - have a read of these - might be useful... https://support.microsoft.com/en-us/kb/840001 Revive Deleted AD Objects - Active Directory Recycle Bin - Microsoft Windows | Windows Server 2008 content from Windows IT Pro

Hmm... Can you post the output to the following commands: get-AutodiscoverVirtualDirectory | fl get-ClientAccessServer | fl get-webservicesvirtualdirectory |fl get-oabvirtualdirectory | fl get-owavirtualdirectory | fl get-ecpvirtualdirectory | fl get-ActiveSyncVirtualDirectory | fl Also - do you have a proper SAN certificate installed?

That's expected accessing it from a web browser. You should get a 600 error. Try using the Test-OutlookWebServices commandlet in PowerShell... that might shed some light on it.

Hmm... I'm a bit stumped now. I'll have a think.