(TIL) Today I Learned...

[icecream-guy]

Today I learned about DNS glue records. apparently there were some circular references in the zone files I needed to fix.

[deanwebb]

Today I learned about DNS glue records. apparently there were some circular references in the zone files I needed to fix.

Glue records?



What are glue records?

[icecream-guy]

Today I learned about DNS glue records. apparently there were some circular references in the zone files I needed to fix.

Glue records?



What are glue records?

DNS records that glue stuff together.

A glue record is simply the association of a hostname (nameserver, or DNS ) with an IP address at the registry.
https://wiki.gandi.net/en/glossary/glue-record

Thanks Gandi

p.s. I liked this statement from that link above
"Glue records are needed when you want to set a domain's nameservers to a hostname that is a subdomain of the domain itself. "

[wintermute000]

In plain language, if the DNS servers your domain points to are in the same domain (hence resulting in circular logic), then you need a glue record to show what the IP is.

[DesertFox]

This month I have learned how useful mnemonics are. The "Real Women Date Engineers In Combat Armor" helped a lot with CCNA CyberOps.

[deanwebb]

Two weeks ago, I learned a ton of stuff about ServiceNow.

Chances are, I'm gonna learn a lot more about it in the days and weeks to come...

[Otanx]

Yesterday I Learned... the part I was missing with MPLS and MP-BGP. I didn't realize that a label was included as part of the NLRI in the BGP advertisement. Once I realized that then everything clicked, and makes sense.

-Otanx

[wintermute000]

LOL wait till you get deeper in the MPLS rabbit hole like BGP-LU and unified MPLS. I LOVE this stuff but as I work in enterprise space primarily, I don't get to do this for realz (and if I wanted to I'd likely have to go back down a seniority/pay grade or two.... sigh)

[deanwebb]

TIL...

... about SNMP inform messages.

They're like traps, but will keep sending until the other side responds affirmatively that it has received the SNMP inform.

https://kb.juniper.net/InfoCenter/index?page=content&id=KB4380&cat=SNMP&actp=LIST

[deanwebb]

TIL that there's such a thing as bypass mode for UPS devices.

[config t]

TIL.. people CAN get fired for incompetence in this organization. Well, removed from the work site anyway, permanent gov'ment employees are almost impossible to fire.

Nice as a person. But jeebus i'm glad we are getting a new boss that has experience 

TIL that there's such a thing as bypass mode for UPS devices.

LOL.. I learned that lesson a while back in my network technician days. Did you dump power from the whole stack?

[deanwebb]

No, this was when a customer was trying to test our gear for HA in a data center...

[deanwebb]

TIL where to find username and domain info in Windows registry.

Computer\HKEY_CURRENT_USER\Volatile Environment

[Otanx]

It was yesterday, but continuing today...

Wrote my first Ansible playbook. I have been using Ansible for awhile, but always using pre-made playbooks, and just editing the vars and Jinja templates. This time I couldn't reuse an existing playbook. I have a bunch of files that contain IP addresses that we need to import into our blackhole router. Each file is named the change ticket number that approved the blackhole of the IPs. I need to read in all these files into one dict. Then use them in a template to create the static routes.

I think this is really cool (and kind of funny):
My template has this line:

Code Select Expand


ip route {{ route }}/{{ ansible_bl_routes[ticket][route]["mask"]|default(ansible_bl_routes[ticket]["mask"])|default(ansilbe_bl_default_ipv4_mask) }} {{ ansible_bl_routes[ticket][route]["next_hop"]|default(ansible_bl_routes[ticket]["next_hop"]|default(ansible_bl_default_ipv4_next_hop }}


and produces the line:

Code Select Expand

ip route 1.1.1.1/32 192.0.2.1

of course it will produce that line 1,000 times with different IPs, masks, and next hops. I have a default mask and next hop that can be over ridden by a per ticket value, or a per route value. So my global defaults are /32 and null0. However, I can override the mask to say blackhole 10.0.0.0/8 on my public edge routers. By adding the following to the file;

Code Select Expand


12345:
  "10.0.0.0":
    mask: "8"



-Otanx

[Otanx]

Learning all the things. In the last week I have expanded on my Ansible skill set. I have learned;
1. How to setup a python virtual environment (virtualenv /var/venv/network-ansible)
2. How to add 3rd party modules into Ansible playbooks. If they are written correctly just dump them in the right directory, and the filename is the name of the task you use in the playbook.
3. How to move a virtual environment. Just copy the entire directory structure. Then look for broken sym-links and fix them. Also may need to fix permissions on everything.
4. How to write a RPM spec file. Not 100% sure I have this figured out. It isn't failing out yet... Has been running for about 15 minutes. Maybe I acidently RPMed the entire linux install? Need to be able to package the venv to be deployed to a bunch of systems.

At home I have also installed Ansible on a Raspberry Pi, and got it to talk to my home gear. Not doing much with it yet, but it is working. Took about 45 minutes, and a lot of that was syntax errors in the playbook. This automation thing is pretty useful, and cool.

-Otanx