Infrastructure Tiers

• Presentation Tier
• Web Server
• Portal Server
• Cache Server
• Print Server
• WAP Server
• Business/Application Tier
• Application Server(Weblogic, WAS)
• Mail Server(SMTP,POP)
• Fax Server(Hylafax)
• SMS Server
• Integration Tier
• Messaging Server(MQ)
• Directory Server(LDAP, Exchange)
• Resource Tier
• Database Server
• FTP Server
• NFS Server
• Directory Server
• Report Server 
• Replication Server
• Systemic Tier
• Load Balancing Server
• Certificate Server(SSL)
• Security Server(Syslog-ng, IDS-Intrusion Detection Server)
• Monitoring Server(Nagios, CA-Health, Introscope)
• Time Server(NTP)
• DNS Server
• Backup Server