Shulou(Shulou.com)06/03 Report--

Common error reports on web pages

200 request completed

301URL pages are permanently moved

302URL page is temporarily moved to temporarily upgrade the website, and the client continues to use the original URL

304cache. This is returned if expires is added to nginx.

Syntax error of 400 client request?

401 request requires user's identity authentication

404 No page found

403 access denied

405 No access

499 is similar to 502, the website does not respond. It may be that this IP visits a lot, blocking the IP that appears 499.

This command to filter IP should be able to say it directly, which is very common.

500 server internal error

502 error. Generally speaking, the nginx balanced backend server did not start or hang up.

The entire main station reports 502.

Ping domain name, DNS is no problem

Check the front-end nginx error log

Check the balanced server at the back end.

The number of tomcat requests is too large and the memory is insufficient (out of memory) oom

503 server failed to respond

504 gateway timed out because the backend response is too slow

Uptime look at the load

Look at the tomcat log, tomcat connection to the database timed out

Found that the database CPU load exceeds 80%

Some queries are found to take too long.

Look at the nginx log to see which server timed out.

The timeout of the gateway may also be due to a large number of requests received maliciously by nginx, to see if an IP has too many requests.

If the server is about to crash and you can't even read the log, you can only drop the process kill and check the log first.

Awk'/ 2017 awk 21 print $1}'| sort | uniq-c | sort-nr | more

Add IP to the blacklist-An INPUT-s IP-j DROP

The server does not support the requested version of the HTTP protocol.

The web request is very slow.

Client network speed problem

Server connectivity ping

Too much web content loading leads to too slow

Database query is slow

The server is overloaded

Google browser F12 to see network

It could also be a web code problem.

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