Troubleshooting Methodology
This represents the absolute first step a technician must take when managing a support ticket or reacting to an automated system alert.
What is identify the problem?
This is the specific term given to a "chunk" of data packaged with a protocol header at any given layer of the OSI stack.
What is a protocol data unit (PDU)?
If an interface is disabled due to a spanning tree or port security violation, a Cisco show interface command will report this specific status.
What is down/error disabled?
Using canonical notation, this double-colon place marker can replace one contiguous series of zeroes, but it can only be used this many times in a single address.
What is once?
This encrypted, secure version of HTTP is assigned to transmit web traffic over TCP port 443 by default.
What is HTTPS (HTTP Secure)?
This specific questioning style should be used initially with users to let them explain issues in their own words and avoid making premature assumptions.
What are open questions?
The Transport layer uniquely identifies a specific network application by assigning and tagging a segment with this identifier.
What is a port number?
This switch component uses Content Addressable Memory (CAM) to map and cache physical ports to the hardware addresses it has seen.
What is a MAC address table?
This non-routable address scope is automatically configured for every active IPv6 interface and always begins with the designated prefix fe80::/10
What is a link local address?
In this specific FTP data transfer mode, the client sends a PASV command, and the server opens a random high port for the client to connect to.
What is passive mode?
"Did it ever work?" and "What has changed since it was last working?" are the two key questions asked during this phase of identifying symptoms.
What is determining if anything has changed?
This type of protocol interaction describes how a protocol running at a specific layer on one node communicates directly with its corresponding layer on another node.
What is a same layer interaction?
This specific error counter increments on a switch interface when an incoming frame is smaller than the minimum permissible Ethernet size of 64 bytes.
What is a runt?
This exact 64-bit interface identifier format is derived by splitting a 48-bit MAC address in the middle, inserting the digits fffe, and flipping the 7th bit.
What is an Extended Unique Identifier-64 (EUI-64)?
This software suite allows UNIX or Linux machines to share files directly with Windows clients by using the Server Message Block (SMB) protocol.
What is Samba?
In this specific troubleshooting style, a technician starts diagnosing at the layer most likely causing the issue, then works up or down the stack based on test results.
What is the divide and conquer approach?
This specific OSI layer administers the dialog between a client and a server, managing the data transfer and eventually tearing down the connection.
What is the Session layer (Layer 5)?
This specific diagnostic log event occurs when a loop causes a switch to clear its MAC table mappings repeatedly because it sees the same address on multiple ports.
What is MAC address flapping?
IPv6 completely eliminates this traditional IPv4 address type, replacing its functionality with well-known multicast addresses instead.
What is a broadcast address?
This type of database stores information in highly structured tables linked by unique IDs and is operated using Structured Query Language (SQL).
What is a relational database (or RDBMS)?
This final step of the methodology ensures that future technicians can review past incidents to see if a historical solution applies to a new case.
What is document findings, actions, and outcomes?
This layer is responsible for transforming data between the format required for network transmission and the format required by an active software application.
What is the Presentation layer (Layer 6)?
A technician should hard-code both ends of a link instead of using autonegotiation to prevent this performance-degrading issue, which causes high packet loss and late collisions.
What is a duplex mismatch?
This transition protocol allows Windows hosts to transmit IPv6 packets over an IPv4 network by encapsulating them as UDP messages over port 3544.
What is Teredo?
This mail submission protocol subset uses explicit TLS via the STARTTLS command and requires client authentication over port 587.
What is SMTP Submission?