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Linux managing DNS servers (LPIC-2)

Quick command reference

lsb_release -d          # get Linux distro and version
cat /etc/centos-release

# ubuntu
sudo /etc/init.d/bind9 {start | stop | restart}

sudo -u bind rndc status

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BGP neighbor states

• Idle:
  • Trying to initiate a TCP connection and listening for TCP connections from peers
  • Admin disabled (neighbor shutdown)
  • Router is waiting before next retry
• Connect: BGP initiates the TCP 3-way handshake.
  • If successful, send Open msg and change to OpenSent.
  • If failed, reset the ConnectRetryTimer and move to active state.
• Active: Trying to establish TCP connection; no BGP messages yet sent
• OpenSent: TCP connection exists and this router has sent the first message to establish the BGP neighbor relationship

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Ansible setup, configure, and ad hoc commands deep dive

Ansible is an automation engine that allows for agentless system config and deployment. Ansible operates over SSH and runs Ansible modules on remote systems to complete tasks.

TOC

• Ansible setup
  • Installing ansible
  • Configuring SSH and sudo for ansible
• Ansible configuration
  • The ansible configuration file

• Setting up the ansible inventory

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Linux essentials

TOC

• Package management
  • RPM based
  • Debian based: APT and dpkg
• Command-line basics
  • Command-line syntax
  • Basic commands

• Command history and completion

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Buffers

keys	Action
:ls	list open buffers
:b3	go to third buffer
:bn	buffer next
:bp	buffer previous
:bp	buffer delete (close)
:e .	browse working directory

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ACI API calls

ToC

• Authenticate
• Get all tenants
• Create / delete tenant
• Create / delete application profile
• Create / delete EPG
• Create / delete VRF
• Create / delete bridge domain

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Provisioner

$ kubectl get storageclasses
NAME                   PROVISIONER                                         RECLAIMPOLICY   VOLUMEBINDINGMODE      ALLOWVOLUMEEXPANSION   AGE
local-path (default)   rancher.io/local-path                               Delete          WaitForFirstConsumer   false                  4d18h
nfs                    cluster.local/nfs-nfs-subdir-external-provisioner   Delete          Immediate              true                   97m

PV (not associated with the storage class)