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CCNA 1
Networking Fundamentals
44
Engineering
Professional
10/23/2008

Additional Engineering Flashcards

 


 

Cards

Term

What does CSMA/CD stand for

 

and where does it apply?

Definition

Carrier Sense Multiple Access / (with) Collision Detection

 

Applicable on half duplex ports

Term
What happens when a collision occurs over Ethernet?
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)

Term

What can break up a collision domain?

What can break up a broadcast domain?

Definition

collision domain: switches, bridges, full duplex host connections

broadcast domain: routers, vlan

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

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

Term

Identify the duplex, media, and length of the following

10-BASE 5

10-BASE 2

10/100-BASE T

100-BASE FX

1000-BASE T

1000-BASE ZX

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

Term

Name the acronym and order the layers of the

OSI Model

Name the type of PDUs used at each layer.

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)

Term

Name and order the layers of the

TCP/IP Model

(and list the corresponding OSI layers)

Definition
4. Application = Application, Presentation, Session
3. Transport = Transport
2. Internet = Network
1. Network Interface = Data Link, Physical
Term

Identify the protocol

(full name, OSI layer, port, transport type)

FTP

Definition

File Transfer Protocol

Application Layer

port 20, 21

TCP

Term

Identify the protocol

(full name, OSI layer, port, transport type)

SMTP

Definition

Simple Mail Transfer Protocol

Application Layer

port 25

TCP

Term

Identify the protocol

(full name, OSI layer, port, transport type)

POP3

Definition

Post Office Protocol v. 3

Application layer

port 110

TCP

Term

Identify the protocol

(full name, OSI layer, port, transport type)

NTP

Definition

Network Time Protocol

Application layer

port 123

UDP

Term

Identify the protocol

(full name, OSI layer, port, transport type)

TFTP

Definition

Trivial File Transfer Protocol

Application layer

port 69

UDP

Term

Identify the protocol

(full name, OSI layer, port, transport type)

DNS

Definition

Domain Naming System

Application layer

port 53

TCP / UDP

Term

Identify the protocol

(full name, OSI layer, port, transport type)

DHCP

Definition

Dynamic Host Configuration Protocol

Application layer

port 67, 68

UDP

Term

Identify the protocol

(full name, OSI layer, port, transport type)

NNTP

Definition

Network News Transfer Protocol

Application layer

port 119

TCP

Term
What happens when establishing a TCP connection?
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)
Term

What are the 3 main elements of Positive Acknowledgement and Retransmission (PAR)

Definition
* Sender will re-transmit a segment if the timer expires before an ACK
* Sender has record of all segments waiting ACK
* Receiver ACKs a segment with the next sequence number expected
Term

What is the TCP sliding window?

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

Term
Describe the rough layout of the TCP header
Definition

__________________________

[ Source port | Dest. port ]

[ Sequence number ]

[ Ack number ]

[ misc. | win size ]

[ checksum | urgent ]

[ options ]

Term
Describe the rough layout of the UDP header
Definition

_______________________

[ source port | length ]

[ dest. port | checksum ]

Term

Identify the protocol

(full name, OSI layer, port, transport type)

CDP

Definition

Cisco Discovery Protocol

Data Link layer

n/a

n/a

Term

Identify the protocol

(full name, OSI layer, port, transport type)

ICMP

Definition

Internet Connection Management Protocol

Network layer

n/a

n/a

Term

Identify the protocol

(full name, OSI layer, port, transport type)

ARP / RARP

Definition

(Reverse) Address Resolution Protocol

Network layer

n/a

n/a

Term

What layer do the following device types operate on:

Hubs

Repeaters

Switches

Bridges

Routers

Definition

Hubs / Repeaters : L1

Switches / Bridges : L2

Routers : L3
Term
What are three main forms of flow control at layer 4?
Definition

congestion avoidance

window size

buffering

Term
What does collision detection require for half-duplex links?
Definition
A loopback circuit for collision detection.
Term
What does the MTU stand for and what does it determine?
Definition

Maximum Transmission Unit

Detemines the max size of the packet that can be sent from the specified interface.

Term
What kind of interfaces do/do not show up in the ARP table for a router?
Definition
Ethernet interfaces (not serial interfaces)
Term
What are the characteristics of a DHCP Discover message?
Definition

From client to server

Broadcast on L2

UDP port 67

Term
What are the characteristics of a DHCP Offer message?
Definition

From DHCP server to client

unicast on L2

UDP port 68

Term
How does DHCP check for address conflicts during IP address assignment?
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.

Term

What are the full names and basic functions of the following router redundancy protocols:

 

HSRP

 

VRRP

 

GLBP

Definition

Hot Standby Router Protocol: Elects an active and standby router; active assumes a virtual IP & MAC and handles all routing to the gateway.

 

Virtual Router Redundancy Protocol: Selects a master router to be the active gateway; all others are standby

 

Gateway Load Balancing Protocol: Load balances over multiple gateway routers; one virtual IP, many virtual MAC

Term

How does priority work for HSRP/VRRP/GLBP?

 

What is the range and default priority?

Definition

Highest priority becomes the active/master/AVG

 

If priority is the same fo all devices, then highest IP on shared subnet becomes the active/master

 

Priority range is 0-255, default is 100

Term

How many groups are supported in HSRP v1 and v2?

 

What are the MAC address ranges for each?

 

What is the default group?

Definition

HSRP v1: 0000.0C07.AC00 through 0000.0C07.ACFF

(00 = Group 0, FF = Group 255)

 

HSRP v2: 0000.0C9F.F000 through 0000.0C9F.FFFF

(000 = Group 0, FFF = Group 4095)

 

Default group is 0

Term

What multicast IP addresses does HSRP v1 use?

 

What multicast IP(v6) and port does v2 use?

 

What multicast IP does VRRP use?

 

What multicast IP and port does GLBC use?

Definition

HSRP v1 uses 224.0.0.2

 

HSRP v2: 224.0.0.102, UDP 2029

 IPv6 multicast link-local destIP FF02::66

 

VRRP: 224.0.0.18

 

GLBC: 224.0.0.102, UDP 3322

Term

What does the preemption setting do for HSRP/VRRP?

 

What is the default setting?

Definition

Enabling preemption allows new routers being added to subnet with a higheer priority than the current active router to immediately take over as the new active router.

 

By default, preemption is disabled for HSRP.

By default, preemption is enabled for VRRP.

Term

What does object tracking do for HSRP/VRRP?

 

Native tracking?

Definition

Object Tracking can be used to automatically decrement HSRP priority of the router based on changes to its routes/connections.

 

Native tracking does the same based on the status of the router's interface (eg. link status and presence of IP addr)

Term

What are the 3 types of HSRP messages?

 

(And any default values/timers?)

Definition

Hello: keepalive indicator of the active router

(Sent every 3 seconds. Standby takes over if none are heard from the active router within 10 seconds.)

 

Resign: used to actively relinquish the active role

 

Coup: force takeover of active role (preemption)

 
Term
What are the operational states of HSRP?
Definition
  • Initial/Disabled: Not ready or able to participate
  • Learn: Not yet determined virtual IP and not yet received hello message from an active device.
  • Listen: Receives hello messages 
  • Speak: Sends/receives hellos; temp state during election/preemption
  • Standby: Monitors active for take over
  • Active: Forwarding traffic; sends hellos
Term
What forms of authentication are available for HSRP/VRRP/GLBP?
Definition

HSRP v1: none

 

HSPR v2: MD5 authentication

 

VRRP: none or plain text

 

GLBP: none, plain text, MD5

Term

How many groups/virtual routers does GLBC support per physical interface?

 

How many virtual MAC addresses per group?

Definition

Max of 1024 virtual routers/groups supported

 

 

Max of 4 virtual MACs (AVF) per group

Term

How does GLBC election work?

 

(Define AVG, SVG, AVF, SVF)

Definition

1. Highest priority elected Active Virtual Gateway

 

2. AVG assigns a max of 4 Active Virtual Forwarders (virtual MAC) to devices in group with highest priority

 

3. 2nd highest priority elected Standby Virtual Gateway

 

4. If more than 4 routers, the rest become Standby Virtual Forwarders

Term

In GLBC, how do the virtual routers repond to a client packet in normal operation?

 

When the AVG is down?

Definition

Client sends packet to virtual IP.

 

Normally, AVG handles the packet and sends back the virtual MAC (AVF) for the client to use. (Can be different MAC per client up to 4, hence load balancing.)

 

If AVG is down, SVG handles traffic for both the AVG MAC and its own. It also sends gratuitous ARP to clear the CAM table of connected switches, and ARP table of clients.

Term
What are the 7 common values that define an IP flow for Netflow?
Definition

Unidirectional sequence of packets common values: 

  1. Source IP address
  2. Destination IP address
  3. Source port number
  4. Destination port number
  5. Layer 3 protocol type
  6. ToS
  7. Input logical interface
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