Term
What does CSMA/CD stand for
and where does it apply? |
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Definition
Carrier Sense Multiple Access / (with) Collision Detection
Applicable on half duplex ports |
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Term
| What happens when a collision occurs over Ethernet (collision domain)? |
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Definition
1. Jam signal sent by hosts involved in collision
2. All hosts involved briefly stop transmitting
3. Hosts each run a backoff algorithm (waits a random time before retransmission) |
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Term
What can break up a collision domain?
What can break up a broadcast domain? |
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Definition
collision domain: switches, bridges, full duplex host connections
broadcast domain: routers, vlan
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Term
Identify the common name, speed and IEEE spec of of the following: 10-BASE 5 10-BASE T 100-BASE T 100-BASE FX 1000-BASE T 1000-BASE SX |
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Definition
10-BASE 5/T : Ethernet, 10Mbs, 802.3 100-BASE T/FX : FastEthernet, 100Mbs, 802.3u 1000-BASE T : GigabitEthernet, 1000Mbs, 802.3ab 1000-BASE SX : GigabitEthernet, 1000 Mbs, 802.3z |
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Term
Identify the duplex, media, and length of the following
10-BASE 5
10-BASE 2
10/100/1000-BASE T
100-BASE FX
1000-BASE ZX |
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Definition
10-BASE 5 : Half, Thicknet, 500 m
10-BASE 2 : Half, Thinnet, 185 m
10-BASE T : Half, UTP, 100 m
100-BASE T : Half/Full, UTP, 100 m
1000-BASE T : Full, UTP, 100 m
100-BASE FX : Full, Multi-mode Optic, 400 m
1000-BASE ZX : Full, Single-mode Optic, 100 km |
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Term
Name the acronym and order the layers of the
OSI Model
Name the type of PDUs used at each layer. |
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Definition
Open Systems Interconnection Model:
7. Application (Data)
6. Presentation (Data)
5. Session (Data)
4. Transport (Segment)
3. Network (Packet)
2. Datalink (Frame)
1. Physical (Bits) |
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Term
Name and order the layers of the TCP/IP Model
(and list the corresponding OSI layers) |
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Definition
4. Application = Application, Presentation, Session
3. Transport = Transport
2. Internet = Network
1. Network Interface = Data Link, Physical |
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Term
Identify the protocol
(full name, OSI layer, port, transport type)
FTP |
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Definition
File Transfer Protocol
Application Layer
TCP port 20, 21 |
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Term
Identify the protocol
(full name, OSI layer, port, transport type)
SMTP |
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Definition
Simple Mail Transfer Protocol
Application Layer
TCP port 25 |
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Term
Identify the protocol
(full name, OSI layer, port, transport type)
POP3 |
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Definition
Post Office Protocol v.3
Application layer
TCP port 110 |
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Term
Identify the protocol
(full name, OSI layer, port, transport type)
NTP |
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Definition
Network Time Protocol
Application layer
UDP port 123 |
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Term
Identify the protocol
(full name, OSI layer, port, transport type)
TFTP |
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Definition
Trivial File Transfer Protocol
Application layer
UDP port 69 |
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Term
Identify the protocol
(full name, OSI layer, port, transport type)
DNS |
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Definition
Domain Naming System
Application layer
TCP / UDP port 53 |
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Term
Identify the protocol
(full name, OSI layer, port, transport type)
DHCP |
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Definition
Dynamic Host Configuration Protocol
Application layer
UDP port 67, 68 |
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Term
| What happens when establishing a TCP connection? |
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Definition
Three-way handshake:
1. A --> B : SYN with seq(A)
2. A <-- B : SYN with seq(B), ACK with seq(A+1)
3. A --> B : ACK with seq(B+1) |
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Term
| What are the 3 main elements of Positive Acknowledgement and Retransmission (PAR) |
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Definition
1. Sender will re-transmit a segment if the timer expires before an ACK
2. Sender has record of all segments waiting ACK
3. Receiver ACKs a segment with the next sequence number expected |
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Term
What is the TCP sliding window? |
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Definition
TCP sliding window is a method for the receiver to negotiate the transmission rate of the sender. Large window = large number of segments sent before ACK'ed. S --> R : X number packets, window size = X S <-- R : ACK of Yth packet, window size = Y S --> R : Y number packets, window size = X |
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Term
| Describe the rough layout of the TCP header |
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Definition
__________________________ [ Source port | Dest. port ] [ Sequence number ] [ Ack number ] [ misc. | win size ] [ checksum | urgent ] [ options ] |
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Term
| Describe the rough layout of the UDP header |
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Definition
_______________________ [ source port | length ] [ dest. port | checksum ] |
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Term
Identify the protocol
(full name, OSI layer, port, transport type)
CDP |
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Definition
Cisco Discovery Protocol
Data Link layer
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Term
Identify the protocol
(full name, OSI layer, port, transport type)
ICMP |
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Definition
Internet Connection Management Protocol
Network layer
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Term
Identify the protocol
(full name, OSI layer, port, transport type)
ARP / RARP |
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Definition
(Reverse) Address Resolution Protocol
Network layer
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Term
What layer do the following device types operate on:
Hubs
Repeaters
Switches
Bridges
Routers |
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Definition
Hubs / Repeaters : L1
Switches / Bridges : L2
Routers : L3 |
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Term
| What are three main forms of flow control at layer 4? |
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Definition
congestion avoidance window size buffering |
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Term
| What does collision detection require for half-duplex links? |
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Definition
| A loopback circuit for collision detection. |
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Term
| What does the MTU stand for and what does it determine? |
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Definition
Maximum Transmission Unit Detemines the max size of the packet that can be sent from the specified interface. |
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Term
| What kind of interfaces do/do not show up in the ARP table for a router? |
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Definition
Ethernet interfaces do show up.
Serial interfaces do not show up. |
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Term
| What are the characteristics of a DHCP Discover message? |
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Definition
Sent from client to server
Broadcast on L2 network over UDP port 67 |
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Term
| What are the characteristics of a DHCP Offer message? |
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Definition
Sent from DHCP server to client
Unicast on L2 network over UDP port 68 |
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Term
| How does DHCP check for address conflicts during IP address assignment? |
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Definition
During address assignment, DHCP checks for conflicts using ping and gratuitous ARP.
If a conflict is detected, the address is removed from the pool. The address will not be assigned until the administrator resolves the conflict. |
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Term
| What are the 7 common values that define an IP flow for Netflow? |
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Definition
Unidirectional sequence of packets common values:
- Source IP address
- Destination IP address
- Source port number
- Destination port number
- Layer 3 protocol type
- ToS
- Input logical interface
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Term
| What is a gratuitous ARP and what is it for? |
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Definition
ARP Response that was not prompted by an ARP Request.
It is way for a node to broadcast/update its IP to MAC mapping to the entire network. |
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Term
| What are the characteristics of a half duplex, and full duplex connection. |
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Definition
half duplex: Only one device can use the wire at a time. Connections are considered multipoint.
full duplex: Devices can send and receive at the same time. Connections are considered point-to-point. |
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Term
| What happens to collision detection on a switch port when a device is connected to it at full duplex? |
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Definition
| The collision detection circuit is disabled. |
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