dns-check

In any migration or Disaster Recovery (DR) process I always ask myself the same questions:

• Are all the DNS created, which ones are missing
• Do they target the right endpoint?
• Do they depend on from where are we trying to connect (local direct, local vpn, local zscaler, remote vpc,...)?
• Are FW and Proxy rules working for those endpoints?

This little script helps me identify what's missing and what isn't working.

Exec

$ python3 dns-check.py -h
usage: dns-check.py [-h] [-f DNS_FILE] [--d] [--env ENV]

options:
  -h, --help   show this help message and exit
  -f DNS_FILE  DNS Excel file to check, default 'DNS_Entries.xlsx'
  --d          Enable Debug
  --env ENV    Environment

Excel Format

Sheet Name: DNS_List Columns:

• Env: environment, can be filtered with --env argument
• DNS: FQDN to check
• Type: A or CNAME
• Target: IP or FQDN depending on Type
• TCP: TCP port number or empty, if not empty check Target tcp connectivity to that port number
• Ping: TRUE/FALSE, if TRUE check Target supports ping/icmp
• NS1: IP of Main DNS resolver
• NS2: can be empty or IP of Secondary DNS resolver

Excel Report

Reports created on existing excel file as new sheets. Sheet Name: CHECK__%Y%m%d%M%S There's a conditional formatting (red row) on those which Status is not OK.

• Env: environment
• DNS: FQDN to check
• Type: A or CNAME
• Target: IP or FQDN depending on Type
• NS: DNS Resolver used
• Status: Can be, MATCH (DNS, Type and Target exists and are OK), NO_EXIST (DNS doesn't exist or can't be resolved by NS), NO_MATCH (DNS and Target exist but don't match)
• TCP_Connectivity: OK or N/A if not available
• Ping: OK or N/A if not available
• DNS_ANSWER: The value obtained from NS