Buscar
Estás en modo de exploración. debe iniciar sesión para usar MEMORY

   Inicia sesión para empezar

level: Chapter4

Questions and Answers List

level questions: Chapter4

QuestionAnswer
what is DHCP ?Dynamic Host-Configuration Protocol (DHCP) - A Dynamic/Automatic method to assign IP Addresses . - Not only IP Addresses: - Subnet Masks - Gateways - DNS!! - Assignment will be for a specific amount of time (default 24 hrs.)
What is DNS ?- Domain Name Server: resolve a URL to an IP Address and vice-versa . - also, there is a reverse DNS (for that vice-versa thing)
which method and port does DNS use ?UDP port 53 .
assignment time of DHCP ?- after 50% of assignment time begins, some checks will happen for each Client, and again after 87.5% of the assignment time, another check Will take place.
dhcp process order?..
what if the first router (Gateway) wasn’t a DHCP Server!!??- there will be a “Helper-Address” . - known as “DHCP Relay” . - help redirecting the broadcast message from the first Gateway to the Correct DHCP Server .
what is (FHRP) ?First Hop Redundancy Protocol . what if the gateway went down!!!!!!!! - a redundant gateway must be there .
What protocols will FHRP use ?- Hot-Standby Redundancy Protocol (HSRP)(cisco only ). - 2 Gateways - No Load-Balancing - Virtual-Router Redundancy Protocol (VRRP) (same of above but open standard) - Gateway Load-Balancing Protocol (GLBP)( cisco only) - 4 Gateways , Load balancing .
what is (NAT) ?Network Address Translation - Private IP Addresses don’t carry Internet! - Public IP Addresses can’t be assigned to private devices! - Then!!!, NAT will translate Private to Public and vice-versa *NAT is done ONLY ONLY by Routers, no Switches, no MLS’s
two ways to apply NAT ?- it can be: Static: one-one translating Dynamic: Group-Group Translating
what is PAT ?It provides wider options as one address can be used for more than one device by specifying the IP address with the port number . - PAT (Port Address Translation) . - also called NAPT, or NAT-Overload - PAT will do a one-65535 Translation!!!
what is NTP ?- we have to stay synchronized - give a precise information, with real timing and date - either by setting an inner clock manually - or asking someone to inform us about timing. - each network device can either be a Server or a Client
which method and port does NTP use ?uses UDP = 123
what Stratum (NTP server ) is needed ?- how preferred and accurate this source is starts from 0 – 15. the closest, the better. - by default: a cisco router = 8
which command NTP use to tell " I am NTP srver " ?ntp master
which command NTP use to tells " That is NTP server " ?ntp server <some IP >
what is SNMP ?Simple Network Management Protocol (SNMP) . - Monitor Networks from a single point of view - Server/Agent Relationship
which method and port does SNMP use ?- uses UDP 161/162
server/agent in SNMP ?- the server is thee requester (and recorder) - at the agent side: - MIB Object (The Factory) - Agent (The Messenger)
- SNMP versions ?- v1: obsolete [dead] - v2c: enhanced [dead] - v3: supports Authentication & Encryption [alive] ptrg an example of GUI program using SNMP
what is Syslog ?System Loggings (Syslog) - stay aware of “everything” - know all what’s happening behind the scenes (or even in front of) - starts from the obvious informations up to “Emergencys”
server/client in Syslog ?- Server can be a Normal Server that collects all the loggings - Server can use the “Syslog” or “Splunk” Software - client is the networking device that generates logs
what is the message '0' (syslog) ?0 = Emergency
what is the message '1' (syslog) ?1 = Alert
what is the message '2' (syslog) ?2 = Critical
what is the message '3' (syslog) ?3 = Error
what is the message '4' (syslog) ?4 = Warning
what is the message '5' (syslog) ?5 = Notification
what is the message '6' (syslog) ?6 = Information
what is the message '7' (syslog) ?7 = Debug
what is QoS ?Quality of Service (QoS) - if traffic was more than bandwidth! - if congestion WILL happen, can some traffic be more preferred than another!? - Generally, UDP will be preferred over TCP (TCP will automatically do A retransmission).
QoS will prefer based on Variety of Factors, some are ?ll
what is classification and Marking, Queueing ? (Qof)- Classification & Marking: classifying the traffic according to its importance (Very High, High, Med, Low) - Queueing: - giving a specific priority to every type of packet (giving the priority of "very high" to the "UDP" traffic) - dividing the Transmission capacity with respect to the priority (giving 40% to the very high, 20% to the high, etc.)
what is policing and Shaping ? (QoS)- Policing & Shaping: - Policing is counting the traffic before transmitting it, and limiting it (limit the FTP traffic to be transmitted at maximum of only 2Mbps) *counting the desired traffic, and dropping all that exceeds - Shaping limits the Queued traffic to a certain amount of traffic, and what EXCEEDS, wait at the queue .
what is SSH ?Secure Shell (SSH) - A secured and trusted method to log in a device remotely. - encrypt the transmitted information - uses the server/client relationship - a replacement for Telnet - needs an application for (Microsoft Windows Users) .
what port and method does SSH use ?what uses tcp port 22
what is FTP ?File Transfer Protocol (FTP) - can devices transfer data between them? - data like Files, Software Images, Configs saved as Texts
what port and method does SSH use ?- FTP uses TCP 20,21! - 2 TCP ports for 2 reasons: - TCP 21 (Control Channel): to establish connection between Server and Client - TCP 20 (Data Channel): to transfer Data between Server and Client
Trivial FTP (TFTP) ?- uses UDP 69 - UDP so, unreliable, but still has it’s uses .