how long 1800 seconds

I read an article two days ago saying that if the satellite orbit cycle is 90 minutes, How many times does the satellite circle around a day? (Observe from space, not from the ground, because the earth's rotation needs to be considered on the ground)

Before configuring the bind DNS server software: Bind is an open source DNS (domain name System) protocol implementation that contains all the software required to query and respond to domain names. It is the most widely used DNS server on the

First, I declare that I am only a programmer, not a professional DBA. The following article describes how to solve a problem, rather than giving you a correct result from the beginning, if there is something wrong with this article, please correct

You must know the tcp_keepalive settings and tcp_keepalive settings. 1. parameter settings View related parameters Sysctl-a | grep tcp_keepaliveNet. ipv4.tcp _ keepalive_intvl = 30Net. ipv4.tcp _ keepalive_probes = 2Net. ipv4.tcp _ keepalive_time = 1

This article describes in detail how to encrypt a wireless router. What specific operations should we perform? I believe that reading this article will help you. 1. enable WEP encryption on the Wireless Router First, let's give an example to

First, Function introduction In the promotion, we can tell each other, our micro-letter public account is what, customers can go to search, and then attention. Two-dimensional code to provide us with a great convenience, as long as a simple scan,

Wireless RouterMore and more widely used in the family, many friends buy wireless routers mainly to make laptop wireless Internet access more convenient, but friends who use wireless routers do not know how to change their ownWireless Router

Statistics | online | Number in the forum someone asked me how to count online numbers? I don't know what the best way is. The following is the implementation of the principle of the site, I wrote it for your reference. This is only my method,

In the forum, someone asked me how to count online numbers? I don't know what the best way is. The following is the implementation of the principle of the site, I wrote it for your reference. This is only my method, certainly not the best, but also

From: Http://blog.51cto.com/lijichao/308509/proc/sys/net/ipv4/icmp_timeexceed_rateThis led to the famous "Solaris Middle Star" when traceroute. This file controls the rate at which ICMP Time Exceeded messages are