| Question | Answer |
| what layer does HDLC function at | layer 2 |
| how does PPP perform error detection | link quality management - (Can tak down a link based on the percentage of errors on the link using LQM |
| PP looked link detection? | Magic number - (The telco might reflect the data that a router sends back to the router to test a circuit. PPP uses a feature called a magic number to detect a looped link and takes down the link) |
| PPP authentication | PAP or CHAP |
| what does synchronous mean with regard to protocols like PPP or SDLC | There is an imposed time ordering at the links sending and receiving ends. Typically the CSU provides the clocking |
| What do you need for a full mesh in frame relay | Virtual Connections between all sites |
| How does Frame relay do addressing | DLCI (Data link connection identifier) |
| what layer does SONET function at | layer 1 |
| size of an IPX address | 80 bits (48 for node, 32 for network) |
| Apple Talk address size | 24 bits 8 for node, 16 for network |
| according to RFC 793 tcp performs what functions | multiplexing using ports, error recovery, flow control using windowing, connection establishment and termination, end to end ordered data transfer, segmentation |
| what type of router memory is used to store the OS used for low-level debugging and not for normal operation | ROM |
| IN IOS how to do you disable all debugging processes | no debug all |
| if you are logged in over a PTY how do you view console messages | terminal monitor |
| cisco IOS boot sequence | the router performs a power-on self test, routers loads and runs bootstrap code from ROM, the router finds the IOS or other software and loads it, the router finds the config file and loads it into memory |
| how do you change the IOS image the router will boot into | boot-system [ROM | FLASH filename ] |
| to avoid loops all bridges do what | use STP and STP places each port into a blocking or forwarding state |
| how does STP determine the root bridge | 1st "bridge priority" then lowest mac address |
| how many bytes is the priority filed in the BPDU | 2 bytes |
| STP describes what states for a port on a switch | Listening, learning, disabled |
| Describe the Listening State with how it relates to STP | listenes to incoming Hello messages to ensure there are no loops, but does not forward traffic or learn mac addresses on the interface. Interim state between blocking and forwarding |
| describe the learning state with how it releates to STP | still listens to BPDUs, plus learns MAC addresses from incoming frames. It does not forward traffic |
| How long does it take for a port to go from listening, learning, to forwarding with default timers | 50 seconds |
| a vlan creates what | a new collision, broadcast domain |
| how does ISL work | It encapsulates the entire ethernet frame with a new header and trailer |
| how does 802.1q work | it inserts a new 4 byte header into the middle of the original ethernet frame which is used to identify the VLAN number |
| where does the 4 byte vlan ID go in the frame when you're using 802.1q | DEST, SRC, Ethernet Type, Priority, VLAN-ID |
| if you would like to see interface status without all of the extra stuff what command would you issue in IOS | show ip int brief |
| what is the interval in which CDP packets are sent? | 10 seconds |
| what is the purpose of CDP | to tell whether a link is up or down if an interface doesn't receive 3 updates (default 30 seconds) it will set the link as down. |
| How do you turn off CDP on an interface within IOS | no keepalive |
| how do you change the timer associated with CDP in IOS | keepalive <interval> |
| you have a back to back cable connected to the router how can you tell which side is the CDE | show controllers |
| if you are using a back to back cable between routers what is true about your time source | its not there and thus you need to set it using the IOS command "clock rate <num> |
| ! ping response code in IOS | ping received |
| "." ping response code in IOS | nothing was received before timeout |
| "U" ping response code in IOS | destination unreachable |
| "N" ping response code in IOS | network unreachable |
| "P" ping response code in IOS | port unreachable |
| "Q" ping response code in IOS | ICMP source quench |
| "M" ping response code in IOS | Can't frag packet to big |
| "?" ping response code in IOS | unknown packet received |
| in order to do hostname resolution what do you need to setup in IOS | ip name-server && ip domain-lookup |
| how do you view the hosts cache in IOS | show hosts |
| cdp will discover what about the neighbors | device id (typically hostname), address list (ip and datalink), port identifier, capabilities list (information on what type of device it is, platform the model and OS level running on the device |
| how would you see CDP information on a hostname | show cdp enry <hostname> |
| how do you view CDP information for all of your neighbors | show cdp neighbor |
| what algorithm does EIGRP use to calculate routes | DUAL (diffusing update algorithm) |
| what roles can routers have in EIGRP | successor and feasible successor |
| what is phase with regard to a signwave | phase refers to where the signal is at a point in time- at the top, going down, at the bottom, going up, and so on |
| what is the difference between baud and kbps | (blank) |
| other than syncronous communications PPP supports what other protocols | asynchronous, PAP, and CHAP |
| PRI US how many B and D channels are there | 23 B 1-64k D |
| PRI Eurpope how many B and D channels are there | 30 B and 1 64kbps D |
| when an IDSN modem dials and connections with the D channel what happens to it | The D channel connection never goes away it is used for (out of band signaling) |
| what does DSLAM stand for | DSL access multiplexer |
| what is the difference between v.90 and v.92 | v.92 provides for "modem" on hold, and better speed recog depending on line quality |
| Typical functions of Layer 1 | cabling, connectors (pins), functions of pins, voltage and current, encoding (return to zero etc..) |