Monitoring Exchange Server 2010 : Debugging Network Connectivity (part 2)

2. Using Nslookup to Test MX Record Configuration

You can use the Nslookup tool to verify MX record configuration on an external or Internet DNS server. In order to receive incoming email, an MX record for each of your mail servers that you use as bridgehead servers or Internet mail servers must exist on your external DNS server or servers. For external DNS servers to resolve a mail server’s MX record and contact that mail server, the mail server must be accessible from the Internet and must be configured to contact a correctly configured DNS server to resolve DNS names.

In order to send outgoing mail, you can configure Exchange Server 2010 to use internal DNS servers that resolve external names locally or use a forwarder to an external DNS server. Typically, you configure computers running Exchange Server 2010 as DNS clients of your internal DNS server. On your internal DNS server, you can configure an external forwarder to point to trusted external DNS servers. Alternatively, to send outgoing mail, you can configure computers running Exchange Server 2010 to use a dedicated external DNS server.

To use Nslookup to verify that your MX records are configured correctly for ingoing and outgoing email, you can perform the following procedure on your Mailbox server:

3. Viewing Network Adapter Configuration

If you are experiencing network connectivity problems on a particular Exchange Server 2010 server, you can use a command based on the Get-NetworkConnectionInfo EMS cmdlet to view the network configuration information for all network adapters configured on that server. Typically, you run this cmdlet locally, and it returns information about the network adapters on the server on which it runs. You can optionally specify another server on the network and the FQDN of the domain controller that retrieves data from AD DS. Note that you cannot use the DomainController parameter when obtaining configuration information on an Edge Transport server.

Commands based on the Get-NetworkConnectionInfo cmdlet can display the following fields:

• RunspaceID This displays a GUID that uniquely identifies the session in which an event occurs.

• Name This displays the name of the network adapter. This can indicate the manufacturer and model of the network adapter or an administrator-specified network adapter name.

• DnsServers This displays the DNS servers the network adapter uses. If more than one DNS server exists, the server names are separated by commas.

• IPAddresses This displays the IP addresses used by the network adapter.

• AdapterGuid This displays the GUID that Microsoft Windows assigns to the network adapter.

• MacAddress This displays the media access control address of the network adapter.

The following command returns network connection information for the local server:

Get-NetworkConnectionInfo

Figure 2 shows the output from this command. Some of the fields on the Exchange Server 2010 server on your test network will return different information.

The POP3 service provides email access to clients on port 110. Secure Socket Layer (SSL)-protected POP3 uses port 995. POP3 is a client-to-server protocol in which email is received and held for the user on the Client Access server. Periodically, users check their mailboxes and download mail using the POP3 service. POP3 is built into, for example, Microsoft Outlook Express. It is also built into the Microsoft Internet Explorer browser.

You can use commands based on the Test-PopConnectivity EMS cmdlet to verify that the POP3 service is running correctly. The Test-PopConnectivity cmdlet can be used to test the POP3 functionality on a specified Client Access server for all mailboxes on servers running Exchange Server 2010 in the same AD DS site. You can also specify a single Mailbox server in the site by using the MailboxServer parameter. You can identify a single mailbox by using the MailboxCredential parameter, but to do this, you need to first get the credential information for a specific mailbox by using the Get-Credential PowerShell cmdlet.

For example, the following command prompts for the credentials for the Kim Akers mailbox user and tests POP3 connectivity to the Kim Akers mailbox on the VAN-EX1 Mailbox server:

Test-PopConnectivity -MailboxServer:VAN-EX1 -MailboxCredential:(Get-Credential "adatum\
Kim Akers") | FL

					  

Note that this command prompts for credentials even when you are logged on with the Kim Akers user. Figure 3 shows that connectivity failed in this instance because the MSExchangePOP3 service is not running.

Commands based on the Test-PopConnectivity cmdlet are typically run against the Client Access server on which they are entered. However, you can specify a remote Client Access server in the same Exchange Server 2010 organization by using the ClientAccessServer parameter. You can also use the ConnectionType parameter to specify whether the connection type is Plaintext, SSL, or Transport Layer Security (TLS). For example, the following command tests POP3 connectivity between the Client Access server CAS01 and all mailboxes on all Mailbox servers in the same organization and specifies the connection type as SSL:

Test-PopConnectivity -ClientAccessServer:CAS01 -ConnectionType:SSL

Note:

CREATING A USER TO TEST CLIENT ACCESS SERVER CONNECTIVITY

You need to create a test user account to test connectivity to Client Access servers. To do this, enter the following command in the EMS and follow the prompts:

New-TestCasConnectivityUser.ps1

You can use the TrustAnySSLCertificate parameter to instruct the command to check the POP3 service without generating an error when the SSL certificate does not match the URL of the Client Access server. You can use the MonitoringContext parameter to specify whether the command is run by System Center Operations Manager 2007. Take care, however, that if System Center Operations Manager 2007 is not running, including this parameter causes the command to fail.

If you want to perform only a test logon to a Mailbox server using the POP3 protocol and do not require the command to test the sending and receiving of a message, you can specify the LightMode parameter. If you are using a port other than port 110 to connect to the Client Access server, you need to use the PortClientAccessServer parameter to specify the port used.

IMAP4 is a standard client-to-server protocol for accessing email from an Exchange Server 2010 server local to the email client. Email messages are received and held by the server. A mailbox user can view the heading and the sender of the message and then decide whether to download it. A user can create and manipulate multiple folders or mailboxes on the server, delete messages, or search for messages. IMAP4 requires continual access to the server during the time that a user is working with his or her email messages.

The default port for IMAP4 is 143. SSL-protected IMAP4 uses TCP port 993 to retrieve email through a Client Access server. Note that both POP3 and IMAP4 enable users to receive email messages. SMTP or ESMTP enables users to send email messages.

You can use commands based on the Test-ImapConnectivity EMS cmdlet to verify that the IMAP4 service is working as expected. You can test IMAP4 functionality on a specified Client Access server for all mailboxes on Exchange Server 2010 Mailbox servers in the same Active Directory site, for a specific Mailbox server, or for a specific mailbox identified by its credentials.

The Test-ImapConnectivity cmdlet supports the MailboxServer, -MailboxCredential, ClientAccessServer, ConnectionType, TrustAnySSLCertificate, MonitoringContext, LightMode, and PortClientAccessServer parameters in the same way as previously described for the Test-PopConnectivity cmdlet. For example, the following command tests IMAP4 connectivity from the Client Access server on which it is entered to all mailboxes on the Mailbox server VAN-EX1:

Test-ImapConnectivity -MailboxServer:VAN-EX1 | FL

The following example tests IMAP4 connectivity from the Client Access server CAS01 to all mailboxes on all Mailbox servers on the local site:

Test-ImapConnectivity -ClientAccessServer:CAS01 | FL

The following example tests IMAP4 SSL-protected connectivity from the Client Access server CAS01 to all mailboxes on all Mailbox servers on the local site:

Test-ImapConnectivity -ClientAccessServer:CAS01 -ConnectionType:SSL
-PortClientAccessServer:993 | FL