Flashcards in Vol 2 Part 3: IP Services Deck (69)
What are System Logs (Syslog)?
Sends messages in real time to the CLI. Occurs when an event happens on the network device. Cisco routers and switches default to send Syslogs to the console CLI.
What commands must be used to enable Syslog?
Line con 0
What commands must be used when setting up Syslog while using Telnet/SSH?
Line vty 0 15
Additionally, the command terminal monitor (term mon) must be issued once telnet or SSH access if granted.
CISCO IOS devices automatically store logs in what memory?
What command is used to save Syslogs in the device's RAM?
What command is used in order to set up a Syslog server?
logging host x.x.x.x
You can also use a name instead of an IP if DNS is configured!
What two commands can be used to configure NTP and how do they work?
NTP Master [*stratum level*]
This command sets up NTP to act only as a server to provide time, with the time derived from the internal clock of the device.
NTP Server [*address* | *hostname*]
This sets up your device to act as both a client and a server. Once the clock is synchronized, it supplies timing to other NTP clients.
Stratum level refers to what with respect to NTP? What is the level used for best accuracy and what is the default stratum level? How do router hops affect the stratum?
Stratum 1 is the best accuracy. The default level is 8. Every router hop adds one to the stratum, meaning a router two hops away from the master would be stratum 3.
What commands are used to configure a loopback interface?
ip address 172.16.9.9 255.255.255.0
What should you do with the loopback IP with respect to NTP? What commands are used to configure this?
NTP should be configured to use the loopback IP as the timing source. This can be done using the command NTP source loopback 0.
What are the two different Layer 2 discovery protocols?
Cisco Discovery Protocol (CDP)
Link Layer Discovery Protocol (LLDP, vendor neutral)
What devices will CDP discover when used?
All directly connected Cisco devices.
What IEEE standard defines LLDP?
What capability code does LLDP use? What does that code refer to?
B. Refers to the bridge.
Which 2 capabilities does LLDP not identify that CDP does? Hint, the capability code for the first one is "I".
IGMP and the neighbor's platform
What command is used to enable/disable LLDP?
[no] lldp run
What command is used to configure LLDP to enable/disable the transmission of LLDP messages?
[no] lldp transmit
What command is used to configure LLDP to enable/disable the receipt of LLDP messages on an interface?
[no] lldp receive
What is a good practice when setting up a network where each router and switch must have timing synchronized quickly?
Set the clock of each device as close to the current time as possible.
NAT Addressing refers to inside and outside, as well as local and global. Explain what each term means.
Inside- Refers to the permanent location of the host from the enterprise's perspective. The host is INSIDE the enterprise
Outside- With source NAT, the one address used by the host that resides outside of the enterprise. NAT does NOT change this address.
Local- It is the address used for that host while the packet flows within the local enterprise as opposed to the internet.
Global- The address used for that host while the packet flows in the internet.
Explain the 4 types of NAT (Inside local, inside global, outside global, outside local)
Inside local- The private address of the host used while inside of the enterprise.
Inside global- The address a host within your enterprise uses while traversing the internet.
Outside global- a public address used by a host outside of your enterprise
Outside local- This term is NOT used with source NAT. With destination NAT, the address would represent a host outside of the enterprise, but the address used to represent that host as packets pass through the local enterprise.
When configuring NAT, what commands are used to set up the inside and outside portion of the NAT design?
ip nat inside
ip nat outside
What command is used to statically configure a 1 to 1 mapping of IPs using NAT?
Ip nat inside source static *inside-local* *inside-global*
When configuring dynamic NAT, what two commands must be used to set up the NAT pool?
Ip nat pool *name* *first address* *last address* netmask *subnet mask*
Ip nat inside source list *acl number* pool *pool name*
When configuring NAT overload (Port Address Translation/PAT), what command must you use?
Ip nat inside source list *acl number* interface *type/number* overload
Why would you want to use NAT overload (PAT)?
When your number of inside hosts is larger than the number of available public ip addresses you have available.
Which RFC addresses the problem with public IPv4 exhaustion by allocating private address space?
What command would you want to use in order to show hits, misses, interfaces, and access-lists in NAT?
Show ip nat statistics
What are the four characteristics of network traffic that can be managed with respect to Quality of Service (QoS)? Explain what each characteristic means.
Bandwidth- speed of the link in bits per second (bps).
Delay- broken up into one-way and round-trip. One-way delay is the time between sending the packet and it arriving at the destination. Round-trip refers to the time it takes to get to the destination and then receive a reply back. This is also known as LATENCY.
Jitter- the variation in the one-way delay between consecutive packets.
Loss- Number of lost messages, usually reflected as a percentage.