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Questions tagged [availability]

35 questions
107
votes
14 answers

Is Ping a reliable way to check if a server is available?

In my application I am pinging a server and waiting for a response. I am using this to determine whether the server is available and responsive or not. Is this a reliable way of determining availability? I assume a firewall could be filtering icmp…
Peter Kelly
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3 answers

How to manage communication during application downtime?

I've had a lot of experiences lately with application downtime, from both vendors and my own applications. This has got me thinking and as best I can google there isn't really a good or standard way of managing customer communication during downtime…
Brandon
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5
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1 answer

Determine availability zone of AWS IP address

I'm currently using Heroku (which uses AWS) and my program needs to communicate with my own EC2 instance. I've made my EC2 instance in the same Region as Herokus', however, in order to reduce costs further I want to be able to community via the…
Hengjie
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4
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What availability is needed for an E-Mail server to not lose messages?

Setting up an E-Mail server, I wonder, what if it goes down. Do I need a redundant setup in order to not lose incoming mails? Or would it suffice to make sure it doesn't go offline for longer than, say, a day?
Philip
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4
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3 answers

Availability at risk due to one offline Domain Name Server?

A domain can have plenty of name servers registered at there domain registrar. The name servers are picked randomly and not like expected primary first, secondary second and so on. Knowing that, does this mean that when one name server is down,…
Bob Ortiz
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4
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4 answers

System Monitoring Redundancy

I consult in a small business environment where I have two HyperV hosts (with <10 VMs) + a couple other servers. I recently had an issue where one of the HyperV hosts had a CPU issue and it came down, bringing most of my non-critical VMs with it,…
Josh Brower
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4
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1 answer

Which VM Availability Zone is used on Azure if no availability option is selected?

I find the documentation on Azure Availability Zones a bit lacking on details about high availability, so I hope someone here knows these details about some undocumented behaviour. What happens when a Virtual Machine (or any other zonal resource,…
Aleksandar Stojadinovic
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Why may AWS t3.micro in Singapore respond slower than t2.nano in N. Virginia from Bangladesh?

I have a t2.nano instance running in North-Virginia availability zone (us-east-1) for almost 1 year. In hope of reducing latency, I just have deployed the created AMI of that instance to a t3.micro instance in Singapore (ap-southeast-1) zone. There…
Touhid
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3
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1 answer

EC2 Bandwidth between two instance in same availability zone

I'm using an Apache proxy on one server in front of tomcat on a different server. What is the the bandwidth between the two EC2 instances if they are in the same availability zone? Does this have anything to do with the network performance of the…
DD.
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uptime.exe crashing on Windows Server 2008

Can anyone get uptime.exe to run either the /s or /p:n switches on a Windows Server 2008 box without crashing? I realise it's a NT tool and no longer supported, but it worked fine on 2003. I've heard there's a version included in Server core, so I…
fenster
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2
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Lifetime of IIS worker process or AppDomain

I have an ASP.NET app hosted in IIS, and I have automatic worker process recycling/shutdown disabled. I'd like to have a rough idea of how long the app has been running continuously without being re-loaded. My thinking is that one source from which…
G-Wiz
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When an ISP is DDoSed, will its NOC have Internet access?

When an ISP is hit by a huge DDoS attack and its data plane is severely congested, will its Network Operations Center (NOC) have alternative Internet access? I'm curious what would be the industry practice for the backup, alternative Internet…
min
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Website not available everywhere

Today I noticed my website http://mint-nachhilfe.ch/ was down, but other people (located in different networks) said it looks up from there. When I came home, I double-checked, and I can really reach it from here. Also, this website considers it…
Cedric Reichenbach
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1 answer

How to check if redis master is OK?

On the documentation, they advice the monitor command. But it has a 50% performance penalty for the whole system, and how should I do that ? Whatching the ouput using SSH until I don't see anything ? Let's say I have 3 servers: 1 with a redis…
Bite code
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How can I tell which package updates will require a reboot or service restart?

One of our boxes is running Ubuntu 8.04 LTS. Most Ubuntu package upgrades are trivial and don't affect availability much. How do I tell which packages are going to cause an outage before applying them?
jldugger
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