mDNS resolves hostnames locally on a LAN without relying on a central DNS server.

The DHCP version used to distribute parameters and optionally addresses on IPv6 networks.

Reverse DNS maps an IP address back to a hostname using PTR records.

EDNS is a concept or mechanism used in network & dns to extend protocol capabilities DNS.

A DNS SOA record defines the authoritative metadata and timing parameters of a DNS zone.

A mechanism that transmits DHCP requests between subnets.

When DNS records have changed or a workstation keeps a stale response, clearing the local cache and comparing resolutions helps isolate the issue quickly…

Force Windows to release its current lease and request a new IP address from the DHCP server.

Identify the DNS resolvers actually configured on a Windows workstation.

Clear locally stored DNS entries when a site or server points to a wrong address….

Restart the DNS Client service when a troubleshooting workflow specifically requires it.

Check which DNS records are returned for a domain….

DNS and DHCP are two essential network services, but they do not perform the same role. DNS translates names into IP addresses, while DHCP automatically pr…

A VLAN segments an Ethernet network at Layer 2. A subnet divides IP address space at Layer 3. They are often associated, but they belong to two different layers.

Customers no longer get lease after DHCP Snooping's DHCP.

Windows DNS client does not get a response within the time frame.

Windows did not manage to dynamically record its DNS records.

The network becomes very slow or unstable after connection to a new switch.

Diagnose an APIPA 169.254.x.x address or DHCP failure by isolating the client, switch port and VLAN, DHCP DORA exchange, relay or IP helper, scope, server…

Diagnose an inaccessible TCP port end to end by checking DNS, routing, the server listener, host firewall, network ACLs, NAT, and packet captures of the TC…

Investigate Windows Wi-Fi dropouts with netsh wlan, WLAN reports, signal/BSSID, driver, DHCP/DNS and access-point correlation before changing radio settings.

Create a dedicated vMotion network on ESXi or vSphere with VMkernel interfaces, VLAN and MTU consistency, redundant uplinks, vmkping validation, and a pilo…

Create a FortiGate VLAN end to end with an 802.1Q subinterface, IP addressing, optional DHCP, address objects, firewall policies, switch trunking, and vali…

Diagnose Windows DNS resolution by separating IP configuration, DNS servers, suffixes, cache, the exact record being queried, and the network path, using R…

Field workflow to isolate Windows network failures across link, DHCP, IP, DNS, routing, firewall and application layers.

DNS reference for records, resolvers, authoritative servers, delegation, caching and Active Directory zones.

Reference of common ports, protocols and troubleshooting context; a known port never means it should be exposed to the Internet.

Linux field reference for system, processes, systemd, logs, storage, networking, DNS, firewall, accounts and SSH.

Field reference for PowerShell system, service, event, network, storage and remote administration checks.

Active Directory operations reference covering identity, replication, FSMO, DNS, Kerberos, GPO, time, secure channel and health checks.

Tools, diagnostics, commands and resources for administering and troubleshooting FortiGate firewalls and FortiOS.

3CX and VoIP troubleshooting for SIP trunks, DECT, SBC, NAT, RTP, audio quality, certificates, phones and backups.

Defensive resources for phishing, ransomware, compromised accounts, MFA, hardening, firewalls, incidents and backup protection.

Enterprise storage resources for RAID, SMART, NAS, SMB/NFS, iSCSI, MPIO, LUNs, SAN, ZFS, LVM, snapshots, capacity and performance.

Troubleshooting for printers, print servers, SMB scan-to-folder, SMTP scan-to-email, drivers, WSD, TWAIN and WIA.