RDAP is the new whois

You may see the message on websites "Use of the RDAP service is limited to lawful business purposes only". 

RDAP is the Registration Data Access Protocol developed by the IETF as the successor to whois.

Key difference: 

whois returns free text, RDAP returns JSON, making it machine readable and easier to automate. It also supports RESTful web services, allowing for HTTP based queries, error codes, authentication and access control.

RDAP also supports Internationalized Domain Names (IDNs), which are domain names utilizing non-Latin characters. Languages can include Arabic, Chinese, Cyrillic or Devanagari. As DNS is limited to ASCII characters, an ASCII encoding called Punycode (deliberately designed to rhyme with Unicode) is used for name translation.

All that said, whois is still probably more frequently used than RDAP.

What is DNSSEC?

DNSSEC uses a cryptographic signature of DNS records to protect domains against forged DNS answers.

DNSSEC stands for Domain Name System Security Extensions, and comprises a suite of protocols to protect against DNS Spoofing, cache poisoning and man-in-the-middle attacks.

A scenario in layman's terms would be an attack that sends a user to a fake copy of your site. E-commerce and SaaS platforms in particular must take care to ensure they use DNSSEC for added protection.

DNSSEC can be skipped for very early stage projects where DNS server settings may change frequently.

Multi-signer DNSSEC is an additional way to implement DNNSEC. An RFC covers this (note that it is not an Internet Standard however), with contributors from Salesforce and Verisign.

The HTTP 400 Error

The HTTP 400 error translates to Bad Request. It can sometimes be seen when attempting a logon to a website unsuccessfully.

In short, the server cannot process your request - potentially due to malformed URLs, corrupted cookies or outdated DNS data.

You can try flushing the DNS cache as well:

ipconfig /flushdns

which should yield the output "Successfully flushed the DNS Resolver Cache" if successful.

ipconfig's DNS features

ipconfig /displaydns

displays the contents of the DNS Resolver Cache (also known as the DNS cache). 

The DNS cache is a temporary DNS storage on your device holding already visited domain names.

Stuff you might see in there include some complicated microsoft.com related addresses under Record Name. Record type of 1 signifies an IP address (IPv4). Record type 2 (also known as a AAAA record) is an IPv6 address.  Record type 5 is an MX record (mail exchange). MX records show where mail for a domain should be routed to. Multiple MX records may exist for a single domain. Time to live is the time in seconds for the cache entry to expire.

These records represent the content of a DNS reply.

WSL at MS Build 2024

Insights on WSL from MS Build 2024. For example a DNS tunnelling feature has been added to address certain VPN issues.

DNS flaw discovered

Dan Kaminsky, a researcher with IOActive discovered a bug in DNS which allows hackers to conduct "DNS cache poisoning".

Read more on Dan's blog here.