Ubuntu Desktop - 20.04LTS - Apt Update Errors

Hi All,

I have an Ubuntu Desktop 20.04LTS (Focal Fossa 20.04.3) machine that is failing to properly run 'apt update'.

I am getting the following when running 'apt update':

$ sudo apt update

Ign:1 https://security.ubuntu.com/ubuntu focal-security InRelease                           

Err:2 https://security.ubuntu.com/ubuntu focal-security Release                             
  Could not handshake: A TLS fatal alert has been received. [IP: 31.170.160.150 443]

Err:3 http://nz.archive.ubuntu.com/ubuntu focal InRelease
  Could not resolve 'nz.archive.ubuntu.com'

Err:4 http://nz.archive.ubuntu.com/ubuntu focal-updates InRelease
  Could not resolve 'nz.archive.ubuntu.com'

Err:5 http://nz.archive.ubuntu.com/ubuntu focal-backports InRelease
  Could not resolve 'nz.archive.ubuntu.com'

Reading package lists... Done

E: The repository 'https://security.ubuntu.com/ubuntu focal-security Release' no longer has a Release file.

N: Updating from such a repository can't be done securely, and is therefore disabled by default.

N: See apt-secure(8) manpage for repository creation and user configuration details.

Select allOpen in new window

$ lsb_release -a

No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 20.04.3 LTS
Release:    20.04
Codename:   focal

Select allOpen in new window

Checking the IP:

$ dig @8.8.8.8 -t any security.ubuntu.com

; <<>> DiG 9.16.1-Ubuntu <<>> @8.8.8.8 -t any security.ubuntu.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 64332
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;security.ubuntu.com.       IN  ANY

;; ANSWER SECTION:
security.ubuntu.com.    59  IN  AAAA    2001:67c:1562::18
security.ubuntu.com.    59  IN  AAAA    2001:67c:1562::15
security.ubuntu.com.    59  IN  A   91.189.91.38
security.ubuntu.com.    59  IN  A   91.189.91.39

;; Query time: 288 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Mon Aug 23 22:25:57 NZST 2021
;; MSG SIZE  rcvd: 136

Select allOpen in new window

$ dig -t any security.ubuntu.com

; <<>> DiG 9.16.1-Ubuntu <<>> -t any security.ubuntu.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 10286
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 65494
;; QUESTION SECTION:
;security.ubuntu.com.       IN  ANY

;; ANSWER SECTION:
security.ubuntu.com.    19  IN  A   91.189.91.39
security.ubuntu.com.    19  IN  A   91.189.91.38

;; Query time: 16 msec
;; SERVER: 127.0.0.53#53(127.0.0.53)
;; WHEN: Mon Aug 23 22:30:44 NZST 2021
;; MSG SIZE  rcvd: 80

Select allOpen in new window

Odd / interesting that the IP address reported when 'apt' tries to run the update is not the same as when I query DNS locally and also Google's DNS (8.8.8.8).  I get the same IPs from 'dig' and 'ping' - different than 'apt' reports.

I am therefore thinking this is a DNS issue, but that leads to the question:  Why would 'apt' not be resolving the IPs the same as 'ping' and 'dig'?

If necessary, I'll just wipe the machine and start from scratch - it is only running a local mail server for the scanners to talk to and then forwarding emails on, so I could probably wipe and re-create in an hour or so, but I am intrigued as to what is going wrong - seems like a learning opportunity!

Thanks,

Alan.