Does not require specialized software
Security is easier to enforce
Lower cost implementation
Provides a single point of failure
Temporarily holds resolved entries
Used by the server to resolve names
Sent by the client to during a query
Passes authentication information between the server and client
Acts as both a client and server within the same communication.
Requires centralized account administration.
Hybrid mode includes a centralized directory of files.
Can be used in client-server networks.
Requires a direct physical connection between devices.
Centralized authentication is required.
DNS dynamically allocates IP addresses to hosts
HTTP transfers data from a web server to a client
POP delivers email from the client to the server email server
SMTP supports file sharing
Telnet provides a virtual connection for remote access
Routes email to the MDA on other servers
Receives email from the client’s MUA
Receives email via the POP3 protocol
Passes email to the MDA for final delivery
Uses SMTP to route email between servers
Delivers email to clients via the POP3 protocol
Not widely available
Does not support encryption
Consumes more network bandwidth
Does not support authentication
User accounts are centralized.
Security is difficult to enforce.
Specialized operating system software is required.
File permissions are controlled by a single computer.
A computer that responds to a file sharing request is functioning as a server.
One way data flow
Centralized user accounts
Resource sharing without a dedicated server
Initiate data exchanges
Are repositories of data
May upload data to servers
Listen for requests from servers
Provides segmentation of data
Provides encryption and conversion of data
Provides the interface between the applications on either end of the network
Provides control of all the data flowing between the source and destination devices
Ceases all connections to the service
Denies multiple connections to a single daemon
Suspends the current connection to allow the new connection
Uses support from lower layer functions to distinguish between connections to the service