how to read traceroute

Role:A router, gateway that looks at which IP addresses the packet passed through during transmission.Working principle:First send a TTL of 1 UDP packets to the remote host, according to the protocol, the router receives the packet, the TTL value minus 1, when the TTL is 0, the router discards the packet, and sends the sender back an ICMP packet, the packet contains the router's own IP address. Similarly, the host that executes the traceroute host con

the destination IP address, Ask the other party to return a packet of the same size to determine whether two network machines are connected, how much delay. Ping refers to end-to-end connectivity, which is often used as a check for usability, but some virus Trojans force a large number of remote ping commands to preempt your network resources, causing the system to slow down and slow down. Ping intrusion is strictly forbidden as a basic function of most firewalls to provide users with a choice.

generally used to display all connected ports and are represented by numbers. The function of the netstat command is to display network connections, routing tables, and network interface information to let users know which network connections are in operation.[1] When used without parameters, Netstat displays the active TCP connection. Netstat (option)Options-A or--all: Displays the socket;-agroups: Displays the multi-broadcast feature group members list;-H or-- Help: online assistance;-I or--

Lost update: Two transactions update a row of data at the same time, the last transaction update will overwrite the first transaction update, resulting in the first transaction update data loss, which is caused by no lock; 1. Dirty reads: Dirty reading means that when a transaction is accessing the data and the data has been modified, and the modification has not been submitted to the database, another transaction accesses the data and then uses the data.e.g.The original salary for 1.Mary was 1

MySQL InnoDB Transaction isolation level dirty read, Repeatable read, phantom read MySQL InnoDB transactions are isolated at four levels. The default value is repeatable read ). · READUNCOMMITTED ). Another transaction modifies the data but has not yet committed it, And the SELECT statement in this transaction reads th

telnet : The Telnet protocol is a member of the TCP/IP protocol family and is the standard protocol and main way of Internet remote Login service. It provides users with the ability to perform remote host work on the local computer. Use the Telnet

Dirty Read, Phantom Read, and non-repeatable READ + transaction ISOLATION level 1. Dirty read: Dirty read refers to when a transaction is accessing the data, and the data has been modified, and this modification has not been committed to the database, then another transac

Tags: presence IDT does not appear height made Zab repeated modificationsI. Isolation levels and phenomena There are 4 levels of database isolation Read uncomitted, unauthorized reading Read Committed, authorized to read REPEATABLE Read, repeatable reading Serializable, serialization There are 3 types of inconsistenci

Tags: count set InnoDB Department CTI hard disk redo log independently completedThere are four transaction isolation levels for Mysqlinnodb: ( default is repeatable read REPEATABLE read) UNCOMMITTED Read Uncommit : The data was modified in another transaction but not yet committed, and in this transaction the SELECT statement may query for these uncommitted data

　　Main content:1. Initial file operation2. Read-only (R,RB)3. Write only (W,WB)4. Append (A, AB)5. Read and write (r+)6. Write-read (w+)7. Additional write read (A +)8. Other methods of operation9. File modification and another way to open a file handleA. Operation of the initial fileusing Python to

Database transaction isolation level-dirty read, phantom read, non-repeated read, transaction level I. database transaction isolation level There are four database transaction isolation levels, from low to high: Read uncommitted, Read committed, Repeatable

Database transaction isolation level and dirty read, phantom read, non-repeated read, transaction level I. database transaction isolation level There are four database transaction isolation levels, from low to high: Read uncommitted, Read committed, Repeatable

I. Database transaction ISOLATION LEVEL There are 4 isolation levels for database transactions, from low to high to read uncommitted, Read committed, Repeatable read, and Serializable, which can solve the problems of dirty reading, non-repeatable reading, and Phantom reading one by one. √: May appear x: does not appear Dirty

1. Some problematic reads in the transaction: dirty read, non-repeatable read, Phantom readThe dirty read (Dirty Read) transaction T1 updated the contents of a row of records, but did not commit the changes. The transaction T2 reads the updated row, and then T1 performs the rollback operation, canceling the modificatio

I. DATABASE TRANSACTION ISOLATION LEVELThere are 4 isolation levels for database transactions, from low to high, READ UNCOMMITTED,Read Committed,Repeatable read, andSerializable, which can be resolved individually by each of the four levels Problems such as dirty reading, non-repetition reading, and Phantom reading. √: May appear x: does not appear

Dirty read (dirty read) unrepeatable read (phantom problem) Parsing1. Dirty read First, distinguish between dirty pages and dirty data Dirty pages are modified pages in the memory buffer pool. They are not flushed to the hard disk in time, but are already written to the redo log. It is normal to

Ext: http://blog.csdn.net/fatherican/article/details/44966921 1, Dirty Read One transaction reads another transaction, and the pending modification is dirty read. Here's the so-called modification, in addition to the update operation, do not forget, but also includeInsert and delete operations. Consequences of dirty reading: If the latter transaction is rolled back, all changes made to it will be revoked.

4 attributes of a database transaction:Atomicity (atomic): both succeed or fail;Consistency (consistency): After a transaction operation, the database is in the same state as the business rules; for example, after the A,b account transfers, the total amount remains unchanged;Isolation (Isolation): transactions in operations do not affect each other;Persistence (Durability): After a transaction is committed, it is persisted to the database. Dirty read,

Issues arising from transaction concurrency:Dirty reads: One transaction reads data that is not committed by another transactionTransaction 1: Updating a single piece of dataTransaction 2: Read record of transaction 1 updateTransaction 1: Commit commits are calledAt this point, the data read by transaction 2 is data stored in database memory, called dirty reads.The data

Label:form of SQL Server data store Pre-read: Use the estimated information to go to the hard disk to read the data to the cache. Pre-read 100 times, which is estimated to read 100 pages of data from the hard disk to the cache. Physical reads: After the query plan is generated, if the cache is missing the