TCP/IP Services 7 Flashcards
What is static IP address assignment
Each node has its IP address entered manually by an administrator. If the node moves it must be manually reconfigured.
Time consuming and prone to errors. Only assigned to systems with a dedicated functionality such as routers, printers or servers that host applications
Name the two ways to assign IP address
Static and dynamic IP addressing
How can IP addresses be assigned dynamically
By using the DHCP service Dynamic Host Configuration Protocol to automatically assign IP addresses.
A DHCP server enables the scope, the range of IP addresses a subnet mask and the lease period, it automatically leases TCP/IP info to DHCP clients.
List the 4 categories of options for DHCP
Global options
Scope options
Class options
Reserved client options
What are DHCP reservations
Are lease assignments in DHCP that allow permanent IP address configuration. If case of network changes the IP address received the change when the lease is renewed.
Steps in the DHCP Lease process
Node comes online DHCP discovery DHCP offer DHCP request DHCP ACK unused DHCP offers expire
What is BOOTP
A UDP network protocol. Servers assign IP address from a pool of available address to diskless workstation (devices with no storage) computers to obtain an IP address prior to loading an advanced operating system.
What is DHCP relay agent
A service that captures BOOTP broadcast and forwards it through the router as a unicast transmission to the DHCP server on another subnet. Used if there is no DHCP server on the subnet.
What is APIPA
automatic private IP addressing
A service that enables a DHCP Client computer to configure itself automatically with an IP address in the range of 169.254.0.1 to 169.254.255.254
Not routable. Cannot communicate outside of the local subnet. Can initialize TCP/IP and communicate on the local subnet in the absence of an active DHCP Scope
What is ipconfig used for
Entered into the command prompt to display connection specific DNS suffix, IP address, subnet mask and default gateway information.
Use ipconfig /all for additional information about IP configuration
Ipconfig options for DHCP
Ipconfig /release to force release of IP address used by client
Ipconfig /renew requests renewal of an IP address for a client
The system first attempts to obtain a DHCP address and if a DHCP server fails to respond it will switch to APIPA addressing
The ping command is used for
Verifying the network connectivity of a computer. Also checks if the target system is active. Verifies the IP address, host name, and reach ability of the remote system. Uses ICMP to check the connections and listens for reply packets
What are the ping options
You can ping a computer or IP address.
The loop back address of 127.0.0.1 to test if TCP/IP has initialized on individual systems.
Other options enter ping /? at command prompt.
By default packet size are
32 bytes
To change packet size use -1 followed by packet length
What is TTL
Time to live. A value that determines how many hops an IP packet can travel before being discarded
Ping target -i TTL
Default packet count is
Four packets
Specify a night number with the -n option
Ping target -n packet count
What is ping blocking
A security measure used to block incoming packets generated by the ping command
In TCP and UDP networks a port is
The endpoint of a logical connection. All are assigned a number ranging from 0 to 65535.
Three blocks of numbers. Well known, registered, dynamic
Describe the three blocks of ports
Well known ports range from 0 to 1023
assigned for used by common service
Registered ports range from 1024 to 49151
For software makers use
Dynamic or private ports range for. 49152 to 65535
Used by unregistered services needing a temporary connection.
TCP Port 7
& UDP
Ping runs on
TCP Port 20
FTP default data runs on
TCP Port 21
FTP control runs on
TCP Port 22
& UDP
SSH runs on
TCP Port 23
& UDP
Telnet runs on
TCP Port 25
SMTP runs on
TCP Port 53
& UDP
DNS runs on
TCP Port 67
& UDP
DHCP BOOTP server runs on
TCP Port 68
& UDP
DHCP BOOTP client runs on
TCP Port 80
HTTP runs on
TCP Port 110
POP3 runs on
TCP Port 137
& UDP
NetBIOS naming service runs on
TCP Port 143
& UDP
IMAP runs on
TCP Port 194
IRC Internet relay chat runs on
TCP Port 389
& UDP
LDAP runs on
TCP Port 443
HTTPS runs on
TCP Port 3389
& UDP
RDP runs on
UDP Port 69
TFTP runs on
UDP Port 123
NTP runs on
UDP Port 161
SNMP runs on
What is a socket
A communication endpoint in an IP Based network. A socket links an IP address with the port number of a service. Help in delivering data packets to the appropriate application process running in the target node. The address is a combination of the protocol, IP address and port number.
{tcp, 193.44.234.3, 53} is an example of
An IP Address socket
What is a host name
A unique name given to a node on a TCP/IP network. A host name combined with the hosts domain name forms the nodes FQDN fully qualified domain name
FQDNs are
The hostname.domainname
Max length is 255. Each dot section can be up to 63 characters long. A network node can have more than one host name assigned to it. It’s primary name is the nose name the other names are called canonical names or aliases.
A domain is
A grouping of computers in the Internet based on the nature of their operations
Identified by their unique names; com,gov,edu
What is a domain name
A unique name that identifies an entity on the Internet. Also known as site names. Usually registers by organization as their website address
What is DNS
Domain name system
A TCP/IP name resolution service that translates FQDNs into IP addresses. Servers store, maintain, update databases. Responds to DNA client name resolution requests to translate host names into IP addresses.
Name the types of DNS records
Address A IPv4 IPv6 address AAAA canonical name CNAME Mail exchange MX Name server NS pointer PTR start of authority SOA service locator SRV
What is an ANS
Authoritative Name Sever
Responds to name related queries in one or more zones in DNS. ITs function is to delegate to other DNS servers
The DNS hierarchy
Allows DNS servers on the Internet to use minimum number of queries to locate the source of a domain name.
Name the steps in the DNS name resolution process
Client requests DNS name resolution
Checks DNS Cache database
Root name server reads top level domain of that name
DNS server contacts top level domain server
If top level domain cannot resolve IP address sent to second level DNS server
Reaches level where DNS server can resolve the host name
The preferred DNS server provides the client with the IP address of the target host
Name the two kinds of DNS queries
Recursive query where the Client requests that its preferred DNS server find data on other DNS servers. If preferred server cannot resolve the na,e it sends a request to another DNS server
Iterative query when the client requests only the information a server already has in its cache for a particular domain name. If cannot resolve the request it notifies the client but doesn’t forward the request to any other server
What is the HOSTS file
A plaintext file configured on a client machine containing a list of IP addresses and their associates host names. Provides an alternative method for host name resolution. Mostly used for trouble shooting
What is the purpose of TCP/IP commands
Help to ensure smooth connectivity in TCP/IP network. Allows you to gather information about how the systems are communicating
The tracers command
Determines the route data takes to get to a particular destination. ICMP protocol sends out time exceeded messages to each router to trace the route.
The pathping command
Provides information about latency and packet loss on a network. Combines the functionality of the ping and tracert commands.
Can be used to isolate a router or subnet with issues. Displays the degree if packet loss at any given router or link
What is the MTR utility
The my trace route utility combines ping and traceroute into a single function
Used on UNIX based systems
What is FTP
File transfer protocol
A TCP/IP that enables the file transfer of files between a users workstation and a remote host. The FTP daemon or service must be running in the remote host. Commands must be entered in lowercase. Works on the application layer of OSI and TCP/IP models
Works on two TCP channels. Port 20 for data transfer and port 21 for control commands.
What is NTP
Network time protocol
IP the synchronizes the clock times of computers in a network by exchanging time signals. Works on the application layer of both models.
What is SMTP
Simple mail transfer protocol
A communication protocol used to format and send email messages from a client to a server. Uses a store and forward process.
What is POP3
A protocol used to retrieve email messages from a mailbox server. Email messages wait in the mailbox on the server until the client retrieves them.
What is IMAP4
Internet message access protocol version 4. Used for retrieving messages from a mail server. More powerful than POP3.
Can check email header and specific string of characters before downloading
Messages can remain in the server while the client works with them
Can search through messages by keywords
Can access folders other than the inbox
What is NNTP
Network news transfer protocol
Used to post and retrieve messages from USENET
RSS feeds based in this
HTTP is
Hypertext Transfer Protocol
Works on the application layer of both models
Enables clients to interact with websites by allowing them to connect to and retrieve web pages from a server.
Insecure
Uses port 80
HTTPS is
Hypertext transfer protocol secure
Secure version of HTTP
Provides a secure connection between a web browser and a server. Uses the secure socket layer SSL to encrypt data.
Uses port 443
What are TCP/IP interoperability services
Services that run in TCP/IP To create a network where dissimilar systems can securely communicate and share resources.
What is the NFS
Network File System
A client/server application that enables users to access shared files stored in differs types of computers and work with the files as if they were stored locally.
Part of the TCP/IP suite and works on the application layer of the OSI model
What is the SSH
Secure Shell is a program that enables a user to log on to another computer over a network, execute commands, and manage files. Creates a shell or session with a remote system and offers strong authentication methods and ensures that communication are secure over insecure channels
Describe the two versions of secure shell
SSH1 authenticates systems using keys to identify users, host keys to identify systems, session keys to encrypt communication in a single session and server keys the protect the session keys.
SSH2 is more secure. Doesn’t use server keys. Includes a secure replacement for FTP called SFTP secure file transfers protocol.
What is SCP
Secure Copy Protocol uses SSH to copy files securely between a local and a remote host or between two remote hosts.
What is telnet
Telecommunications Network
A terminal emulation protocol that allows users at one site to simulate a session on a remote host as it the terminal were directly attached.
Not secure.
What is SMB
server message block
is a protocol that works on the application layer and helps share resources such as files, printers and serial ports among computers.
Used in samba, an open source product, to enable UNIX and windows machines for sharing directories and files
What is LDAP
Lightweight directory access protocol
Defines how a client can access information, perform operations, and share directory data on a server. Designed for use over TCP/IP networks and the Internet in particular
What is zeroconf
Zero configuration networking. A set of standards that provides for automatic configuration and IP address allocation on both ethernet and wireless networks. Can exist without central control or configuration services such as DHCP or DNS.
typically uses MAC addresses as parameters because they are unique and available on most network devices.
Networks implementing Zeroconf must include methods for four functions
Network layer address assignment
Automatic address assignment using multicast
Translation between network names and network addresses
Location or discovery of network services by name and protocol
