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What's a hostname? Domain name? What's the difference?
A hostname is a user-readable name of a computer/server which usually resides on a specific network, for example, WEBHA1 and WEBHA2 can refer to two servers on the internal network. A domain name is a user-friendly name used to identify a particular website or system of similarly grouped website or services... under the hood, it's an IP address that is registered (DNS), usually pointing to a particular website, for example, qas.g4sreport.com is the name of the domain which contains R360, R360WS, ALNotifications, and more which all reside under this same site... the "domain" is simply the name itself but is oftentimes interchangeably used as the website itself.
The difference between both hostname and domain name is one is referencing the network or system (domain, G4S.com) and the other a particular computer on that network, oftentimes the server (hostname, WEB1)... in mail.yahoo.com "mail" is the single server that deals with emails while "yahoo" is the domain name of the network on which mail and other servers reside.
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I navigate to a website called 'abc.com' and get a "The site can't be reached. The server IP address could not be found.". What's the problem?
The DNS could not find the particular name 'abc.com' and so it couldn't associate an IP address with the address given. Most likely, you either (a) typed a bad URL like www.afaff@8.com or (b) the address is correct but the DNS hasn't been properly configured to point to the IP address yet.
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I navigate to a website called 'abc.com' and get a 500 "Internal Server Error. abc.com is currently unable to handle your request". What's the problem? How would you determine this?
It appears the DNS found the associated IP address correctly and the website is up and running, however, an error on the server occurred as the 500 Internal Server Error is a very general HTTP status code that means something has gone wrong on the website's server, but the server could not be more specific on what the exact problem is.
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I navigate to a website called 'abc.com' and get a HTTP "503 Service is unavailable" error. What's the problem? How would we fix it?
We can first determine that the DNS name has been found, that it is pointing to the correct location, and that the website has been configured for that domain and is currently running... so the system isn't necessary down.
However, the services is temporarily unavailable... perhaps the system is overloaded with too many requests, or the server is temporarily down for maintenance. Also, other issues can cause this status code including a problem with communication between DNS, router, server, load balancer, and so on, making the service unavailable, as such we can try the following,
- (a) Refresh page
- (b) Refresh application pool
- (c) Reboot the server
- (d) Scheduled maintenance work
- (e) Improper firewall or security configurations
- (f) Bad credentials, Database disconnected, or a pulled wire on the network
- (g) Lastly, check application logs on the server having the issues.
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I navigate to a web address of 'abc.com/Images/' and get a HTTP "503 Forbidden: Access is denied." error. What's the problem and how do I fix it? Is there an alternate message?
We are getting a correct response from everything up until the last page/directory. That is, the DNS is working and pointing to the correct address, the Server knows who it is and is running, and the Server is responding to the user's request so it is working; but the user doesn't have permissions to this location. If the location didn't exist, you should receive a 404 File/Directory Not Found error but instead got this error which indicates you likely don't have permission to this folder/file.
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Describe IIS site, applications, and virtual directories.
Sites: A site is a container for applications and virtual directories that you can access through unique bindings: containing both a binding protocol (ie, http or https) and binding information (ip address, port, host headers).
Applications: An application is a group of files that delivers content or a service over various protocols (ie, http, https, smtp, ftp, dns, tls/ssl, pop3, telnet). When you create an application in IIS, the applications path becomes part of the site's URL. In addition to the application belonging to a specific site, it also belongs to a specific application pool which isolates the application from other application pools on the same server.
Virtual Directories: A directory name (aka path) that you specify and map to a physical directory on a local or remote server, then becoming part of the application's URL and which user's can then request access.
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Describe the concept of IIS sites and how they exist to bring about websites.
Concept of Website (aka sites), applications, and virtual directories formalized, each becoming distinct objects which can coexist and can be configured independently of one another (existed previously but not fully enforced). Briefly, they exist in a hierarchial relationship with one or more sites, each site can contain one or more applications and/or virtual directories, each which can then contain one or more virtual directories, and these virtual directories are mapped to a physical directory on the computer or network.
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What's a load balancer and how does it work?
A load balancer is a hardware device or piece of software that sits between the client machine and the server hosting the website. It's an effective tool which allows redundancy in the case of a failure, maintenance, or excessive traffic... switching from one system to the other seamlessly to the user.
When using a load balancer, the DNS, rather than pointing to the server directly, would point to the load balancer which in turn points to the server and visa-versa.
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What are the 5 categories of Http status codes?
- (1) 1xx - Informational, rarely used
- (2) 2xx - Success, client sent a message, server accepted it
- (3) 3xx - Redirection, server received and redirected request
- (4) 4xx - Client error, perhaps the client sent a bad request and the server cannot continue until client fixes error
- (5) 5xx - Server error, server received a good request but failed to perform the error for some reason.
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What are the most common Http status code numbers and their respective meaning?
- (a) 200 - OK (request was successful)
- (b) 201 - Created (item was inserted)
- (c) 400 - Bad Request (client error, server can't complete)
- (d) 401 - Unauthorized (credentials required and failed)
- (e) 403 - Forbidden (authorized, but rights not granted)
- (f) 404 - Not Found (not found or doesn't exist)
- (g) 500 - Internal Server Error (server error, generic response)
- (h) 503 - Service Unavailable (generally temporary)
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