Our subject for this month is Microsoft Exchange Server 5.5.
This is the sixth exam that we have discussed and as such if you have been following the
series and taking the examinations along the way, this will be the final exam for you.
As discussed before when we examined TCP/IP, four out of the six examinations needed for
obtaining MCSE are non-optional, core subjects: Networking Essentials, Windows NT Server,
Windows NT Server in the Enterprise and either Windows 95 or Windows NT Workstation.
Having passed these four examinations, you must then decide upon which two elective
examinations to take. Almost everyone opts to take TCP/IP as one of their two electives,
simply because almost every network runs on TCP/IP and an understanding of TCP/IP is
essential in order to successfully install and administer other applications such as
Internet Information Server, SQL Server or Exchange Server. The second exam to choose as
your elective is a little more open to persuasion. Those that are looking for the simple
life often go for Internet Information Server, as this application is reasonably
straightforward to learn and may already be familiar to them as it comes with Windows NT
Server. SQL Server 5.0 has also proved very popular and is the obvious choice for database
administrators and developers. I have chosen to take you through the Exchange Server 5.5
examination because messaging is at the heart of almost every business and because it can
be learned without too much trouble. In terms of career progression it is a good choice,
being roughly equal to SQL Server in terms of staff requirement in the UK, but without the
additional hassle of learning Structured Query Language (SQL) first.
The exam has 5 sections: Planning, Installation and Configuration, Managing Resources,
Monitoring & Optimisation and Troubleshooting. As usual, we will be taking the exam
one section at a time, listing the different subjects that you could get asked about in
that section and then giving hints and tips on how to answer the types of questions that
you are most likely to come across. The new Exchange 5.5 exam is reputedly quite easy as
Microsoft exams go, but the subject is such a wide one that a lot of background reading or
a good familiarity with the product is strongly recommended. This months article
examines the first of these sections.
The Planning Section
What to Revise
Dial-Up Connections, Public Folders across WAN links, Site Planning, Messaging Connectors,
Client Access Protocols, Configuring DNS, Circular Logging, File Locations, Offline
1. Dial-Up Connections
If you are planning to install Exchange Server on servers at multiple locations that are
connected via dial-up links, you must install servers at each location into separate
sites. Also remember to configure Public Folder Affinity (from Information Store Site
Configuration container properties sheet) for each site that you wish its home mailbox
users to be able to use public folders in other sites.
2. Public Folders across WAN links
The Exchange administrator of a multi-site organisation must decide whether to retain a
single copy of a public folder and allow user access by configuring site affinity, or to
place a replica copy of the public folder on each site where users require access to the
public folder and configure synchronisation between the replicas. The way to decide is to
determine whether the amount of user access traffic would be more or less than the amount
of replication traffic. If users are typically reading information rather than writing
information, it may well be better to go for keeping synchronised replicas on each site,
as the replication traffic will be small. On the other hand, if users are making large
changes or new entries to the public folder, it may be more effective to retain a single
copy to avoid the heavy replication traffic that would otherwise ensue.
3. Site Planning
There are certain rules that must be followed when planning your sites. Each server in the
same site must have a permanent, RPC-capable connection to all other servers within the
same site. Each server must use the same site service account as all other servers within
the same site. Although these are the only two absolute rules, sites are also often
affected by language, geographical area and the responsibilities of administration teams.
4. Messaging Connectors
There are four types of messaging connector, each with its own advantages, disadvantages
and reasons for choosing it.
||This uses the Exchange native message format to
transfer mail between sites. As such it is more efficient than any other connector type as
there is never any need to reformat the data. However, the site connector is limited to
only connecting Exchange sites to other Exchange sites and has no scheduling or maximum
message size configuration options. Use it to connect Exchange sites together when
bandwidth is not an issue.
||This uses the ITU (International
Telecommunications Union) X.400 mail message format to transfer mail. As such it can be
used to connect an Exchange site to any other mail system that also accepts the X.400
standard. Because it is a different format, mail needs to be translated before sending and
after receiving, so it is not as efficient as the site connector. It does have the ability
to be configured for scheduling and message size limits. Use it to connect Exchange sites
together when bandwidth is limited and to connect an Exchange site to a different
messaging system that accepts the X.400 standard.
|Internet Mail Service
||The Internet Mail Service (IMS) uses the
Internet mail message format SMTP (Simple Mail Transfer Protocol). Again, mail requires
translation before sending and after receiving and can be sent to or received from any
messaging system that complies with the SMTP RFCs (Request For Comments). As with the X400
connector, the Internet Mail Service is not as efficient as the Site connector but can be
configured for scheduling and message size limits. Use it to connect to either another
Exchange site or any SMTP-capable message system via the Internet.
|Dynamic RAS Connector
||The Dynamic RAS connector is more limited in its
capability as it can only connect two Exchange sites together via a dial-up link. The
Dynamic RAS Connector uses the Exchange native format to transfer mail and can be
configured for scheduling and message size limits.
5. Client Access Protocols
The following are protocols that clients can use to interact with Exchange Server
||SMTP (Simple Mail Transfer Protocol) is used by
Internet clients to send mail to the server.
||POP3 (Post Office Protocol version 3) is used by
Internet clients to receive mail from the server.
||IMAP4 (Internet Mail Access Protocol version 4)
is also used by Internet clients to receive mail from the server. IMAP4 is more recent
than POP3 and allows more options for security and the way in which the mail is
||LDAP (Lightweight Directory Access Protocol) is
used by Internet mail clients to query directory listings.
||NNTP (Network News Transfer Protocol) is used by
Internet mail clients to send and receive messages in news groups on the Internet.
||MAPI (Messaging Applications Programming
Interface) is used by DOS, Win16 and Win32 clients to send and receive mail, view public
folder information and query the directory.
||RPCs (Remote Procedure Calls) are used by MAPI
clients as the underlying IPC (Inter-Process Communication) transport mechanism. RPCs
require a minimum of 64k bandwidth to work.
When selecting which protocols for your clients to use, bear in mind the 64k
limitation of RPCs. If your clients have a smaller connection than this to the server (for
example dial-up clients using 56k modems) then they cannot use MAPI to access the Exchange
If your users are going to connect via the Internet, then you will probably require a
firewall to prevent hackers from attacking your server from the public Internet. If this
is the case, you must ensure that the firewall is configured to allow the appropriate port
numbers through, depending upon which protocols your users will be using. Because the
default behaviour of MAPI with Exchange is to negotiate a unique port number for the
Information Store service and the Directory Service, MAPI users over the Internet will
need the Exchange administrator to make changes in the registry to specify permanent port
numbers for these two services. Once this is done, the administrator must then allow port
135 and the two ports configured in the registry through the firewall.
6. Configuring DNS
If using the Internet Mail Service, the DNS server must be configured correctly. Each
Exchange Server that is configured to accept inbound messages via the Internet Mail
Service requires both a HOST and an MX record to be created on the DNS server. The HOST
record maps the host name to IP address. The MX record maps the domain name for mail users
to the correct host to send the mail to. MX records can be given a priority number.
Exchange servers should be given equal priority numbers in order to provide load
balancing. An Exchange server with a lower priority number will always receive all of the
mail. An Exchange server with a higher priority number will never receive any of the mail
unless the server with the lower priority number is down. Configure servers with different
priority numbers to provide fault tolerance.
7. Circular Logging
Circular logging is the facility for Exchange to automatically re-use previous transaction
log files once their contents have been fully committed to the database. (The Information
Store and Directory services each maintains its own transaction logs.) By default,
transaction logging is switched on for both services. The setting is configured from the
properties sheet of the server object. Switching off transaction logging means that
previous transaction logs are never re-used, which in turn means that previous logs will
continue to build up on the hard disk until they are deleted. The advantage of this is
that if one of the service databases (IS Private, IS Public or DS) is lost, data can be
restored right up to the last transaction. Conversely, with transaction logging, enabled
data would only be restorable from the time of the last backup, as the transaction logs
will not be complete.
8. File Locations
By default, Exchange server installs to C:\Exchsrvr. If you have a second hard disk it is
recommended that you use the Performance Optimiser utility to move the service databases
(IS Private and IS Public in the C:\Exchsrvr\mdbdata folder and DIR in the
C:\Exchsrvr\dirdata folder) to a different hard disk than the transaction logs. In the
event of a hard disk failure and loss of the databases, the data can be restored from the
transaction logs and the most recent backup tape.
9. Offline Folders and Personal Folders
Clients with laptop computers who sometimes work from home and sometimes in the office, or
clients who always work away from the office may need to be configured for offline
folders. Offline folders allow remote users to store a copy of their mail messages in a
local folder, known as an OST (Offline Store). OSTs allow the user to read and compose
their mail messages whilst offline and then connect just to synchronise their OST with
their mailbox on the Exchange server. Personal folders are also separate files that can be
stored on the local computer, however, mail is moved from the server to a personal folder.
Personal folders are usually used to permanently archive important mail messages that
would otherwise be deleted if left on the Exchange server. Personal Folders (PSTs) can
also be stored on the users home directory on the file server.Both OSTs and PSTs can
be password protected by the user, but if they forget the password, the data will be lost
as there is no administrative way of changing it. If an OST or a PST becomes corrupted,
then the repair utility SCANPST.EXE can be used to attempt a repair.
Next month, Richard Adams will continue his guide to Implementing and Supporting Microsoft
Exchange Server 5.5
Richard Adams is director of SkillShelf an IP
and Internet consultancy and training provider based in London.