Network :Important things to know for handling “The Oracle network infrastructure”

Network bandwidth	Amount of traffic that the network can actually transport
Network latency	time taken between and through network devices
LAN	Local Area Networking
Ethernet Topologies	Bus topology Basic star topology LAN Token Ring Token Ring Topology FDDI (Fibre Distributed Data Interface)
Switches	Used to link several separate LANs.Switch packets between multiple LANs as needed
Internetworking devices	Hubs (concentrators) Bridges Routers Switches
WAN	Wide Area Network
Wide Area Network Topologies	Frame relay Integrated Services Digital Network  (ISDN) Leased line Asynchronous Transfer Mode (ATM)
Measuring Latency	Use ping  to find the PMTU between systems
PMTU	Path Maximum Transmission Unit
ping	ping -f -n <number of pings> -l <size> <destination IP address> Helps verify IP-level connectivity Used to send an ICMP echo to a target name or IP address ping -? shows command-line options available
Netstat	Displays protocol statistics About current TCP/IP connections Can be used with various options netstat -a displays all connections netstat -r displays the route table, plus active connections netstat -e displays Ethernet statistics (may be combined with the -s option) netstat -s displays protocol statistics netstat -n does not convert addresses and port numbers to names
Ipconfig	print TCP/IP related host  configuration
Tracert	Determines the route between hosts (Optimal)
Route	View or modify the route table
tnsnames.ora	TNSNAMES.ORA is a SQL*Net configuration file that defines databases addresses for establishing connections to them. This file normally resides in the ORACLE HOME\NETWORK\ADMIN directory
sqlnet.ora	Sqlnet.ora is a text file that provides SQL*Net with basic configuration details like tracing options, default domain, encryption, etc. This file can be found in the ORACLE HOME\NETWORK\ADMIN directory
Listener.ora	Listener.ora is a SQL*Net configuration file used to configure Oracle Database Listeners (required to accept remote connection requests). This file normally resides in the ORACLE HOME\NETWORK\ADMIN directory or in the directory define by the $TNS_ADMIN variable.
TAF	TAF (Transparent Application Failover) is a configuration that allows session fail-over between different nodes of a RAC database cluster TAF only works for idle sessions and SELECT statements
tnsping	TNSPING is a utility in the ORACLE HOME/bin directory used to test if a SQL*Net connect string can connect to a remote listener (check if the socket is reachable).
Connect String	A connect string is a string used to identify and connect to a remote database. Connect strings are defined in a local TNSNAMES.ORA file, Oracle Names Server or OID directory
LDAP	LDAP (Lightweight Directory Access Protocol) is an application protocol for querying and modifying directory services running over TCP/IP
ldap.ora	The ldap.ora configuration file sets the LDAP properties
SQL*Net	SQL*Net (or Net8) is Oracle's networking software that allows remote data-access between programs and the Oracle Database, or among multiple Oracle Databases
CMAN.ora	CMAN.ORA is a text file containing settings for the SQL*Net Connection Manager (CM)
TNS_ADMIN	TNS_ADMIN is an environment variable that points to the directory where the SQL*Net configuration files (like sqlnet.ora and tnsnames.ora) are located
TWO_TASK	TWO_TASK is an environment variable used to specify that connections should be made to a remote database (via SQL*Net) without specifying a service name (tnsnames.ora entry).
HOST STRING	A host string is the name you assign for TNS connectivity in tnsnames.ora