Tag: VMware

Achievement Unlocked: VMware VCAP 6.5 DCV 3v0-624 Exam – Summary and Tips

I wanted to start off my Monday morning with a bang, so decided to schedule my VCAP 3v0-624 exam for the first in the morning. Well, I passed!

Before walking into this exam, I wasn’t sure if I prepared enough, but I felt kind of comfortable once the exam started. I’d like to share what I did to prepare for this exam, although this is my first ever VCAP-Design.

Summary of Study Material

  1. VMware Education Courses
    1. I took the vSphere: Design Workshop 6.5 course online a few months ago. This was good at providing a fundamental understanding of VMware’s approach to a virtualized design.
    2. However, I’ve taken other design courses (vCloud Director) so I felt that the approach is very similar. While I reflect positively on this class, I think if you’ve taken other design workshop classes and have a firm understanding of the design methodology, you probably can skip (or take another 6.5 class for my next point).
    3. One valuable thing was the instructor was careful to point on what has changed in vSphere 6.5 (or what’s new). This is very important in my opinion for the Design Exam. So again, positive and a good use of time.
  2. Books I read
    1. VMware vSphere 6.x Datacenter Design Cookbook
      1. I thought Hersey Cartwright’s book was solid on giving me a practical understanding of what to expect for a design and items to be thoughtful on.
      2. While Hersey did write this in the vSphere 6.0x days, it’s still very pertinent and covers many of the important business aspects which seem to be overlooked.
    2. IT Architect: Foundation in the Art of Infrastructure Design
    3. While I enjoyed reading this book, I thought there was more VCDX-preparation level material than specific material for this VCAP-Design test. Perhaps it provided me with a well-rounded approach and drove the thought process. Either way, this is one to keep around for any future planning.
  3. Material I used
    1. Print out BOTH the 6.5 Exam Guide AND 6.0 Exam Guide and review both. For my own study method, I ensure I go through EVERY topic and write them out on my whiteboard. I ensure I cover each one to the best of my abilities.
    2. vBrownBag VCAP6-DCV Video Series
      1. This was AWESOME! I spent quite a bit of time going through each video and taking notes.
      2. I felt this material was very pertinent to the 6.5 Design Exam. Although the Visio drawings are not on the test anymore, the design methodologies remain constant and everyone did a great job of walking through each subsection.
    3. VMware Material
      1. Review the VMware Validated Design Material
      2. I downloaded ALL vSphere 6.5 new documents, along with the following:
        1. vSphere 6.5 DRS Performance Whitepaper
        2. Deploying Extremely Latency Sensitive Applications in vSphere Whitepaper
        3. vSphere 6.5 Virtual Machine Encryption Performance Paper
        4. vSphere 6.5 What’s New? Whitepaper vmw-white-paper-vsphr-whats-new-6-5
        5. vSphere 6 Fault Tolerance: Architecture and Performance Whitepaper
        6. Platform Services Controller 6.0 Topology Decision Tree
        7. vSphere Availability – VMware vSphere 6.5 Document 
        8. vSphere Storage – VMware vSphere 6.5 Document
          1. I was pretty comfortable here, so did not review all of this since it’s the standard documentation.
    4. Other Material
      1.   CADs- Constraints, Assumptions (Risk, Requirements) & Dependencies- see attached.
      2. Conceptual_Logical_Physical_It_is_Simple – see attached
      3. Design Example – pretty sure I found this on the VMware Community Forum. design examples – conceptual,logical,physical
    5. vCommunity Material – honestly, this was a huge component as many others have created some great material out there. This is not in any order, all is good and pertinent.
      1. Graham Barker’s VCAP6-DCV Exam Preparation Guide – very detailed for Sections 1 and 2. I loved how he created sample tests to gauge your knowledge of each section.
      2. Matt Callaway’s VCAP6-DCV Design Study Guide – links to many of the videos but other applicable notes he created.
      3. Hersey’s write-up on exam experience and study notes – again, very good and the callout for the books too.
      4. David Stamen’s summary and important notes – I would stress the importance of David’s tips. They are SPOT ON!
      5. Rene van den Bedem’s Availability Explained post – very good and thorough.
      6. VirtualTiers Sample Quiz by Jason Grierson – really cool site that provides a sample design. Again, many of the questions are the Visio-type stitching but drives the thought-process around the design.
      7. vMusketeers VCAP6-DCV Design Quiz – a lot of work was put into this. Again, driving and testing your knowledge

Exam Tips

  1. I think many of the vCommunity members covered a lot of the specific things, but I will point out things that come top of mind.
  2. Know your Requirements, Assumptions, Constraints, and Risks. Practice, practice practice! I had a hard time understanding functional versus non-functional and then it finally clicked for me.
  3. Understand your AMPRS – Availability, Manageability, Performance, Recoverability, and Security. Again, practice these and understand what are the specific metrics and how non-functional requirements can be categorized in each respective role.
  4. Don’t be afraid of reviewing the 5.x and 6.0 VCAP-Design material. Again, all very pertinent.
  5. Be well prepared for anything that has changed in vSphere 6.5. There are many things that may have changed or enhanced so you’ll need to have knowledge of these aspects.
  6. Last of all, make sure you have working knowledge of design scenarios. I think this has to come with experience and dealing with actual customer situations. This does come with time and exposure.

Post-Exam Thoughts

  1. I thought the exam was very challenging, yet fair. Like I said before, this is my first VCAP-Design, so I cannot comment about the Visio-drawings that were required (albeit I heard these were difficult).
  2. Expect a lot of thought process on each question. TAKE YOUR TIME, you will have plenty of time. I had an hour left even after reviewing every question twice.
  3. Expect the multiple choice, select “x”, and drag and drop.
  4. Go with your instinct and ensure you read the questions clearly.

I hope this helps others – cheers!

-Daniel

Photon OS – no ping and no ICMP replies? Other quick hints on Photon too.

Updated – July 9th, 2020 with password policy and complexity.

So I’ve been playing with Photon OS recently with a few of our Cloud Provider solutions, very nice lightweight appliance.

However, one thing that surprised me is the minimal/lightweight install does not have ping installed nor can you ping it (ICMP echo replies). In my opinion, this is a basic function for any type of network troubleshooting. I understand it’s minimal…but go cut something else out. 🙂

So how do we set up some basic network functions?

Setting up a Static IP

cd to /etc/systemd/network

vi (or use your preferred text editor) a file called 10-eth0.network

There’s three sections required: Match, Network, and DHCP

Below is the code required:

[Match]
Name=eth0
[Network]
Domains=HOSTNAME domain.local
Gateway=192.168.110.1
Address=192.168.110.61/24
DHCP=no
[DHCP]
UseDNS=false

Save it (wq!), and now it’s time to chmod the file so it can be read by the OS

chmod 644 10-eth0.network

Now we should see the correct permissions: 

Now restart the network daemon service.

systemctl restart systemd-networkd

Complete!

Installing Ping on Photon OS

Pretty easy – as you can see, doesn’t exist. 

Now there’s two different versions of Photon – version 1 and 2. On version 1, it’s pretty easy – type in the following:

yum install iputils

Now for Photon 2.0 (which I’m currently using), repos are disabled by default and so I was getting a message stating “package not found” which was odd. However, digging in further, I found the repos were not enabled.

Enabling Repos so we can pull iputils

cd /etc/yum.repos.d/

I enabled three repos:

photon

photon-extras

photon-updates

We need to edit each file and change the enabled=0 to enabled=1

Once I did this, run “tdnf repolist” and we should now see the following:

Now let’s install it!

tdnf install iputils

Now we should see the following: 

Sucess! Ping is available now, along with netstat too.

Allow ICMP echo responses

This is a change in the firewall table. By default, ICMP echo and replies are dropped.

Here are the two commands required to enable ICMP traffic:

iptables -A OUTPUT -p icmp -j ACCEPT
iptables -A INPUT -p icmp -j ACCEPT

Before I make the change on my system, I’m unable to ping

Make the iptables change….

Voila! We now get a response. 

DNS Configuration

Currently, I found a DNS issue with the vami_config_net file with a Photon 3.0 appliance deployment – it was not setting the DNS correctly and resorting to a 127.0.0.53 address. Moreover, the /etc/resolv.conf file should not be modified and if it is, changes do not persist post-reboot.

Two options:

  1. Set DNS inside of the /etc/systemd/network/10-eth0-static.network network configuration file
  2. Change it under /etc/systemd/resolved.conf

Option 1 Example:



1
2
3
4
5
6
7
[Match]

Name=e*



[Network]

Address=198.51.0.2/24

Gateway=198.51.0.1

DNS=198.51.0.1

Option 2

root@vcav [ ~ ]# more /etc/systemd/resolved.conf 

.......
# See resolved.conf(5) for details

[Resolve]

DNS=10.96.88.2

#DNS=

#FallbackDNS=8.8.8.8 8.8.4.4 2001:4860:4860::8888 2001:4860:4860::8844

#Domains=

LLMNR=false

#MulticastDNS=yes

#DNSSEC=no

#DNSOverTLS=no

#Cache=yes

DNSStubListener=yes

Resetting the Root Password

I’ve had situations where I’ve locked myself out of a Photon instance. The process is pretty simple – follow this link: https://github.com/vmware/photon/blob/master/docs/photon_troubleshoot/resetting-a-lost-root-password.md

Removing Password Expiration Policy

By default, Photon has a one year password expiration policy for accounts, including the root account. One can modify this and establish a no expiration policy, but also adjust other parameters.

From a root account, one can see the following:

root@vcd [ ~ ]# chage -l root

Last password change					: Mar 30, 2020

Password expires					: Mar 30, 2021

Password inactive					: never

Account expires						: never

Minimum number of days between password change		: 0

Maximum number of days between password change		: 365

Number of days of warning before password expires	: 7

One can modify this by using the “chage” command.

chage -m 0 root

From there, we can now see the password expiration has been removed.

root@vcd [ ~ ]# chage -l root

Last password change : Mar 30, 2020

Password expires : never

Password inactive : never

Account expires : never

Minimum number of days between password change : 0

Maximum number of days between password change : 99999

Number of days of warning before password expires : 7

Password Complexity

Photon utilizes the standard PAM modules for password complexity. For those of you in a lab environment that utilize the same password or standard password methodology, one might need to adjust this.

The configuration file is under:

/etc/pam.d/system-password

We can see under this file that we have three lines –

root@usagemeter42 [ /etc/pam.d ]# more system-password 

# Begin /etc/pam.d/system-password

password    requisite   pam_cracklib.so     minlen=8 minclass=4 difok=4 maxsequence=0 retry=3 enforce_for_root

password    requisite   pam_pwhistory.so    retry=3 remember=5 enforce_for_root

password    required    pam_unix.so         sha512 shadow use_authtok

# End /etc/pam.d/system-password

For me, I wanted to just disable the policy in its entirety. To do this, comment out the first line:

# Begin /etc/pam.d/system-password

#password    requisite   pam_cracklib.so     minlen=8 minclass=4 difok=4 maxsequence=0 retry=3 enforce_for_root

password    requisite   pam_pwhistory.so    retry=3 remember=5 enforce_for_root

password    required    pam_unix.so         sha512 shadow use_authtok

# End /etc/pam.d/system-password

From there, one can change their password –

root@usagemeter42 [ /etc/pam.d ]# passwd

New password: 

Retype new password: 

passwd: password updated successfully

Setting the Hostname

Need help changing it from the default photon-appliance hostname?

Hostnamectl is the command for permanently changing the name – not just editing the /etc/hosts file.

hostnamectl set-hostname DanielApp-B

Reboot the system.

One last tidbit – SSHD not starting?

During some of my testing, my lab environment went bottoms up – thanks, Timo 😉

After my Photon appliances started back up, I could not SSH to them. So after some troubleshooting and help from the VMware internal team, figured out what happened.

Steps to resolve:

Log into the console and ls -l /var/vmware/skip_sshd and you can also check the status of sshd by typing “systemctl status sshd”

If the file does exist, you need to remove it. No clue why it was added when I had a hard power outage, but it did.

rm /var/vmware/skip_sshd

Now start up ssh..

systemctl start sshd

Voila! we can now see it’s started

Now, SSH works! 

Other great details on Photon commands can be found here: Photon OS Troubleshooting Guide

Thanks!