What is the difference between DNS, DHCP and DNS records, and how do you troubleshoot name resolution?

DHCP assigns IP configuration — address, subnet mask, gateway, and DNS servers — to devices automatically through a lease. Without it every device needs manual configuration.

DNS resolves names to addresses. A client asks its configured resolver, which either answers from cache or walks the hierarchy from root to top-level domain to authoritative server.

The record types worth knowing:

• A — name to IPv4 address. AAAA — to IPv6.
• CNAME — an alias pointing to another name.
• MX — mail servers, with priority values.
• TXT — arbitrary text, used for SPF, DKIM, and domain verification.
• NS — the authoritative name servers for a zone.
• PTR — reverse lookup, address to name.

Troubleshooting name resolution, in order:

• Can you reach the IP directly? If yes, it is definitively DNS, not connectivity.
• nslookup or dig against the configured resolver, then against a public one such as 8.8.8.8. A difference means an internal DNS problem.
• Check the client's configured DNS servers — ipconfig /all or resolv.conf. Pointing at a public resolver instead of the domain controller breaks internal name resolution and is a very common misconfiguration.
• Flush the cache — ipconfig /flushdns — since stale entries persist after a record changes.
• Check TTL when a record was recently changed; propagation is really cache expiry.