DevOps-ish

DevOps-ish

Troubleshooting DNS - the internet broke today

3 ways in the command line

blameDNS.jpg Akamai's DNS servers ran into a hiccup today (7/22/21) and it effected some big names, such as Steam, Play Station store, Salesforce, and more. Here are 3 ways to see if it truly is a DNS outage. Pretty much if you get an of these to return, DNS is not a problem. You will receive a timeout error or something similar IF DNS is to blame.

  • Run curl to return the header of the homepage. If you see a HTTP 200/301 or HTTPS 200/301 then you are able to resolve the page:
sshme@pop-os:~$ curl -Isk steam.com
HTTP/1.1 200 OK
Server: nginx/1.15.6
Date: Fri, 23 Jul 2021 02:01:05 GMT
Content-Type: text/html
Content-Length: 4791
Last-Modified: Tue, 30 Mar 2021 01:29:07 GMT
Connection: keep-alive
ETag: "60627ee3-12b7"
Accept-Ranges: bytes
  • A good 'ol nslookup -- If you see an IP address (Address below) returned below the hostname (Name below) it's NOT DNS:
sshme@pop-os:~$ nslookup steam.com
Server:         127.0.0.53
Address:        127.0.0.53#53

Non-authoritative answer:
Name:   steam.com
Address: 43.129.23.233
  • Similar to above, you can use dig to look at the DNS record. If you see an IP address in the ANSWER SECTION, DNS is working:
sshme@pop-os:~$ dig steam.com

; <<>> DiG 9.16.8-Ubuntu <<>> steam.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 41605
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 65494
;; QUESTION SECTION:
;steam.com.                     IN      A

;; ANSWER SECTION:
steam.com.              2664    IN      A       43.129.23.233

;; Query time: 0 msec
;; SERVER: 127.0.0.53#53(127.0.0.53)
;; WHEN: Thu Jul 22 21:03:17 CDT 2021
;; MSG SIZE  rcvd: 54
 
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