Many years ago, networks consisted of repeaters, bridges and router. Switches are the successors of the bridges. A switch is nothing else than a multiport bridge, and a traditional switch doesn’t know how to pass traffic to a different broadcast domains (VLANs). Passing traffic between different broadcast domains, is a job for a router. A router has an IP interface in each broadcast domain, and the IP interface is used by the clients in the broadcast domain as a gateway.

Customers that use HPE 3PAR StoreServs with 3PAR OS 3.2.1 or 3.2.2 and VMware ESXi 5.5 U2 or later, might notice one or more of the following symptoms:

• hosts lose connectivity to a VMFS5 datastore
• hosts disconnect from the vCenter
• VMs hang during I/O operations
• you see the messages like these in the vobd.log or vCenter Events tab

Lost access to volume due to connectivity issues. Recovery attempt is in progress and the outcome will be reported shortly

Recently, a customer has informed me, that copy sessions to encrypted devices failed, after he has made an update to Data Protector 9.07. The copy sessions failed with this error:

|Critical| From: BMA@<hostname> "" Time: <Date><Time>
|90:6111| Error retrieving encryption key.

The customer uses tape encryption. The destination for the backups is a HPE StoreOnce, and a post-backup copy creates a copy of the data on tape. Backup to disk was running fine, but the copy to tape failed immediately.

The Virtual Router Redundancy Protocol (VRRP) was developed in 1998 as an open standard protocol. VRRP is the result of an Internet Engineering Task Force (IETF), and it’s described in RFC 5798 (VRRPv3). VRRP was designed as an open standard protocol, but it uses some patents from Cisco. Its function is comparable to Cisco Hot Standby Router Protocol (HSRP), or to the Common Address Redundancy Protocol (CARP). VRRP solves a very specific problem at the network edge: It offers highly available virtual router interfaces, or in simple words: A highly available default gateway. Its home is the network edge, and because of this, VRRP is a so called first hop redundancy protocol. When moving towards network core, VRRP loses importance. If you move from the network edge to the core, redundancy is primarily offered by dynamic routing protocols and redundant links.

Sometimes you have to check when the last backup of an Exchange mailbox database was taken. This is pretty simple, because the timestamps of the last full, incremental and differential backup is stored for each mailbox database. You can check these attributes using the Exchange Control Panel (ECP), or you can use the Get-MailboxDatabase cmdlet.

Backup successful, but no timestamp?

Take a look at this output. As you can see, there’s no timestamp for the last full, incremental and differential backup. But this database was successfully backuped some minutes before.

When you use Microsoft Outlook in cached mode, what I always recommend, and you add additional mailboxes to your outlook profile, you will notice that the OST file will grow. Outlook will download the mailbox items (mails, calendar entries, contacts etc.), and store them in the OST file. This is the default behaviour since Microsoft Outlook 2010. If you want to disable this behaviour, you have two options:

• Edit the registry
• Use a group policy object (GPO)

Edit the Windows registry

The easiest way is to use a reg file. Copy this text into a file and save it as disablecachedmode.reg. Then double click the file and confirm, that you want to import the registry file.

Edit: If you have already installed .NET 4.6.1, check this blog post on how to remove it (You Had Me At EHLO…)

Microsoft Exchange heavily relies on Microsoft .NET Framework. Because of this, Microsoft provides a matrix for the supported Microsoft .NET Frameworks. Mostly unknown is the fact, that Exchange doesn’t support the every Microsoft .NET Framework, and this is causing trouble sometimes. Some admins simply install the latest .NET releases because “it doesn’t hurt”. Well… it hurts!

Another bug in Exchange 2016 CU2. The Role of a new receive connector is greyed out. You can select “Front-End-Transport”. This is a screenshot from a german Exchange 2016 CU2.

Solution

Use the Exchange Management Shell to create a new receive connector. Afterwards, you can modify it with the Exchange Control Panel (ECP).

[PS] C:\Windows\system32>New-Receiveconnector -Name "Client Frontend Dummy" -RemoteIPRange ("192.168.200.99") -TransportRo
le "FrontendTransport" -Bindings ("0.0.0.0:25") -usage "Custom" -Server "exchange1"

Identity                                Bindings                                Enabled
-------- -------- -------
EXCHANGE1\Client Frontend Dummy         {0.0.0.0:25}                            True

Microsoft has confirmed, that this is a bug in Exchange 2016 CU2.

After deploying a new Microsoft Exchange organization with Exchange 2016, or after deploying a Microsoft Exchange 2016 into an existing organization, you might notice a strange behaviour regarding the Offline Address Books (OAB).

[PS] C:\Windows\system32>Get-OfflineAddressBook

Name                                    Versions                                AddressLists
---- -------- ------------
Standard-Offlineadressliste             {Version2, Version3, Version4}          {\Globale Standardadressliste}
Standard-Offlineadressliste (Ex2013)    {Version4}                              {\Globale Standardadressliste}

Huh?! Where does this Exchange 2013 OAB come from? As you can see in the cmdlet output, there’s no Exchange 2013 in this organization.

Sometimes it’s necessary to have two DNS servers that are authoritative for the same DNS namespace. This is the case if you use the same namespace for your web site and your internal Active Directory domain, e.g. terlisten-consulting.de. Or that you have created the zone terlisten-consulting.de in your Windows DNS to point specific hosts to internal IP addresses. The DNS servers at your ISP would be authoritative, and the domain controllers of your Active Directory would also be authoritative for the same domain. The response to a query depends on which DNS server you ask. So what would happen if you try to resolve www.terlisten-consulting.de, and the internal DNS has no record for it?