CCNA 1 Flashcards
Command to configure IPv6 static default route
Ipv6 route ::/0 interface next-hop
Command to show IPv6 access lists on a router?
Show ipv6 access-list
Command to allow telnet and ssh
Transport input telnet ssh
AAA stands for?
Authentication, authorization and accounting.
What is an API?
A contract that describes how various components communicate and exchange data with each other.
FTP port numbers
20, 21.
How to open debug for nat?
Debug ip nat
What is LLDP?
Link layer discovery protocol
Finds device neighbors.
What is CDP?
Cisco discovery protocol.
Finds device neighbors.
(Doesn’t work with PCs)
What is MSTP?
Multiple spanning tree protocol.
Combines best of PVST & 802.1Q.
Uses 1 root for many vlans.
Speed: fast
Resources: med or high
Trees: one for multiple vlans
802.1s
What is STP?
Spanning tree protocol
Used for vlans.
Ports take ~50sec to boot.
Speed: slow
Resources: low
Trees: one
802.1d
Steps:
- Determine root bridge (by priority, then mac)
- Determine root port.
What does “error-disables” mean?
The port is down.
What is a BPDU?
Bridge protocol data unit
What does BPDU Guard do?
Protects spanning tree.
- disables a port (usually a Port Fast one) if it receives a BPDU.
(BPDUs come from switches)
What is DSCP?
Differentiated Services Code Point (DSCP) is a means of classifying and managing network traffic and of providing quality of service (QoS) in modern Layer 3 IP networks. It uses the 6-bit Differentiated Services (DS) field in the IP header for the purpose of packet classification.
(As opposed to 3-bit with COS)
What is COS?
Class of service.
Provides quality of service (QoS) for networks using 3 bits. Higher is more important.
What is 802.1q?
It is a protocol that allows VLANs to communicate with one another using a router. 802.1Q trunks support tagged and untagged frames.
If a switch receives untagged frames on a trunk port, it believes that frame is a part of the native VLAN. Also, frames from a native VLAN are not tagged when exiting the switch via a trunk port.
The 802.1q frame format is same as 802.3. The only change is the addition of 4 bytes fields. That additional header includes a field with which to identify the VLAN number. Because inserting this header changes the frame, 802.1Q encapsulation forces a recalculation of the original FCS field in the Ethernet trailer.
Note: Frame Check Sequence (FCS) is a four-octet field used to verify that the frame was received without loss or error. FCS is based on the contents of the entire frame.
What is DTP?
Dynamic Trunk Protocol.
DTP allows two interconnected switches to negotiate the operating mode of a link - either an access link or a trunk.
For STP, the host identifier and the bridge identifier will be different or the same for the root (bridge)?
The same.
STP states:
Blocking Listening Learning Forwarding Disabled = discarding - same as blocking in current version.
What is PVST?
Per VLAN Spanning Tree (PVST) is a Cisco proprietary protocol that allows a Cisco device to have multiple spanning trees. The Cisco device can interoperate with spanning trees on other PVST devices but cannot interoperate with IEEE 802.1Q devices. An IEEE 802.1Q device has all its ports running a single spanning tree. PVST+ is an extension of PVST that allows a Cisco device to also interoperate with devices that are running a single spanning tree (IEEE 802.1Q).
PVST+
Speed: slow
Resources: high
Trees: 1 for every vlan.
Rapid PVST+
Speed: fast
Resources: very high
Trees: 1 for every vlan.
What is RSTP?
Rapid spanning tree protocol. Port states: Disabled Discarding = listening + blocking. Learning Forwarding
Port roles: Root Designated Alternate Backup
What is NBAR?
Network based application recognition.
Uses layers 4-7 for deep packet inspection.
Generally used at edge of network.
Passive mode: statistics
Active mode: apply markings and QoS.
What is ICMP?
Internet Control Message Protocol.
It is used by network devices, including routers, to send error messages and operational information indicating success or failure when communicating with another IP address
What is POE?
Power over Ethernet.
