• IMAP (cont’d.)• Disadvantages– Re

• IMAP (cont’d.)
• Disadvantages
– Requires more storage space, processing resources than POP servers
– Network managers must watch user allocations closely
– IMAP4 server failure
• Users cannot access mail
• Additional TCP/IP Utilities
• TCP/IP transmission process
– Many points of failure
• Utilities
– Help track down most TCP/IP-related problems
– Help discover information about node, network
• Nearly all TCP/IP utilities
– Accessible from command prompt
– Syntax differs per operating system
• Ipconfig
• Command-line utility providing network adapter information
– IP address, subnet mask, default gateway
• Windows operating system tool
– Command prompt window
• Type ipconfig and press Enter
– Switches manage TCP/IP settings
• Forward slash ( / ) precedes command switches
• Requires administrator rights
– To change workstation’s IP configuration
• Ifconfig
• Utility used on UNIX and Linux systems
– Modify TCP/IP network interface settings
– Release, renew DHCP-assigned addresses
– Check TCP/IP setting status
– Runs at UNIX, Linux system starts
• Establishes computer TCP/IP configuration
• Used alone or with switches
– Uses hyphen ( - ) before some switches
– No preceding character for other switches
• netstat
• Displays TCP/IP statistics, component details, host connections
• Used without switches
– Displays active TCP/IP connections on machine
• Can be used with switches
• nbtstat
• NetBIOS
– Protocol runs in Session and Transport layers
– Associates NetBIOS names with workstations
– Not routable
• Can be made routable by encapsulation
• Nbtstat utility
– Provides information about NetBIOS statistics
– Resolves NetBIOS names to IP addresses
– Useful only on Windows-based operating systems and NetBIOS
• Limited use as TCP/IP diagnostic utility
• Hostname, Host, and Nslookup
• Hostname utility
– Provides client’s host name
• Administrator may change
• Host utility
– Learn IP address from host name
– No switches: returns host IP address or host name
– On Windows need to down third-party version of host
• Nslookup
– Query DNS database from any network computer
• Find the device host name by specifying its IP address
– Verify host configured correctly; troubleshoot DNS resolution problems
• Dig
• Domain information groper
• Similar to nslookup
– Query DNS database
– Find specific IP address host name
• Useful for diagnosing DNS problems
• Dig utility provides more detailed information than nslookup
• Flexible: two dozen switches
• Included with UNIX, Linux operating systems
• Windows system: must obtain third party code
• Traceroute (Tracert)
• Windows-based systems: tracert
• On some Linux systems: tracepath
• Uses ICMP ECHO requests
– To trace path from one networked node to another
– Identifying all intermediate hops between two nodes
• Transmits UDP datagrams to specified destination
– Using either IP address or host name
• To identify destination
• Several switches available
• mtr (my traceroute)
• Comes with UNIX, Linux operating systems
– Route discovery, analysis utility
• Combines ping, traceroute functions
– Output: easy-to-read chart
• Simplest form
– mtr ip_address or mtr host_name
• Run continuously
• Stop with Ctrl+C or add limiting option to command
• Number of switches refine functioning, output
• Results misleading
– If devices prevented from responding to ICMP traffic
• mtr (my traceroute)
• Windows operating systems
– pathping program as command-line utility
– Similar switches to mtr
– pathping output differs slightly
• Displays path first
• Then issues hundreds of ICMP ECHO requests before revealing reply, packet loss statistics
• Route
• Route utility
– Shows host’s routing table
• UNIX or Linux system
– Type route and press Enter
• Windows-based system
– Type route print and press Enter
• Cisco-brand router
– Type show ip route and press Enter
• Route (cont’d.)
• Route command
– Add, delete, modify routes
• Route command help
– UNIX or Linux system
• Type man route
– Windows system
• Type route ?
• Summary
• Subnetting separates network into multiple segments or subnets
• Creating subnets involves changing IP address bits to represent network information
• CIDR is a newer variation on traditional subnetting
• Last four blocks represent interface in IPv6
• Gateways facilitate communication between subnets
• Different types of address translation protocols exist
• Several utilities exist for TCP/IP network discovery, troubleshooting