I build small tools for the work I do every day, and the ones that are useful beyond my own desk end up here. They run in your browser: no account and no queue, and I do not keep a log of what you look up.
DNS Lookup
Ask Google Public DNS or Cloudflare what they currently resolve for a domain: addresses, mail servers, text records and more. You get that resolver’s answer at this moment, read the same way I read it when a change has just gone in.
What it helps with
- Checking a change. Confirm the records the resolver you pick returns right now, after a migration, a new mail provider or a DNS edit.
- Mail problems. Look at the MX records a domain points to, and the TXT records that carry verification and sender rules.
- Handing it off. Copy the answer, with record names, TTLs and the time it was retrieved, as a readable report for a ticket or a vendor.
CIDR & Subnet Calculator
Work out what a prefix actually covers: the network address, the subnet mask, the wildcard mask, the broadcast address, the address range and the usable host count, for any IPv4 prefix from 0 to 32. Paste an address with its prefix, or enter an address and a prefix or subnet mask in separate fields.
What it helps with
- Sizing a block. Check how many addresses a prefix holds before you write it into a firewall rule, a route or a DHCP scope.
- Reading a range. Turn 192.0.2.130/26 into the network address, the broadcast address and the usable range in one step.
- Handing it off. Copy a plain text report with the mask, the wildcard mask and the range for a ticket or a vendor.
Who this is for
- Technicians who need a quick, honest read on a client’s records without opening a ticket or a terminal.
- Anyone sizing or reading an IPv4 range who wants the arithmetic done once, and done right.
- Anyone with a domain who wants to see what a public resolver answers right now, in plain language.
The automation I build around this kind of work is on the AI & Automation page, and I write up what worked and what didn’t in the lab notes.
The DNS Lookup tool sends your query straight from your browser to the resolver you pick, so that resolver receives it and keeps its own logs. The subnet calculator sends nothing: the address you enter is used in your browser and is never sent to any server. This site does not receive either one, and I keep no history of what you look up here.