In this article you will find descriptions of the individual WEDOS OnLine checks. To create a new check, follow the instructions OnLine – New Check. Administer an existing check according to the article OnLine – Check Management.
In this article, you will find the following check descriptions:
HTTP Check
The HTTP check verifies the functionality of a web URL, detects response errors, measures response time, and checks HTTPS certificate status and expiration. It checks the domain name against the URIBL (blocklist of domain names) and its IP address against the DNSBL.
HTTPS check settings include:
- URL: The complete address that the test checks, including the protocol (http:// or https://).
- IP protocol: Performs the test via the selected IP protocol. When set to auto (default), it prefers IPv6.
- Connection timeout: Maximum time tolerance for connecting to the server. Enter a value of 1 to 5 seconds. The default value is 5 s. If the server does not respond within this time, the test returns an error.
- Response timeout: The maximum time tolerance to return a complete response from the server (including the connection). Enter a value between 1 and 10 seconds. The default value is 10 s. If the server does not return a complete response within this time, the test returns an error.
- Slow: The time in milliseconds after which the test evaluates the server's response as slow. Enter a value between 100 and 5000 ms. The default value is 2000ms. If you delete the value, the test will not evaluate response time.
- HTTP codes: List of HTTP response codes that the test considers a positive response. Enter one or more comma-separated values (e.g. 200, 301), or enter a range a dash-separated range (e.g. 200 - 202). Allowed values are 100 to 599. The default value is 200 (Found status).
- Username and password: If the verified page requires authentication, enter a working username and password. The test does not suppor secure login methods, such as OTP.
- Check certificate trust: The test verifies the HTTPS certificate against trusted certificate authorities and compares the certificate name to the host name. If you want to accept an invalid certificate (e.g. self-signed), uncheck this option.
- Certificate expiration check: The test checks the validity of the certificate and if the validity falls below the number of days set in the certificate warning field (enter 1 - 30 days, default value 7), it sends a certificate expiration warning.
- Check block lists (DNSBL, URIBL): The test checks the presence of IP addresses of HTTP servers or domains in public block lists (DNSBL, URIBL).
For an overview of the HTTP type check output, see the article OnLine – HTTP Warnings and Errors.
Kontrola typu Ping
The Ping check sends ICMP requests to the specified domain name or IP address. It checks the responses received and measures response time.
Ping check settings include:
- Target: The domain name or IP address to be checked by the test.
- IP protocol: Perform the test via the selected IP protocol. When set to auto (default), it prefers IPv6.
- Requests: The number of packets that the test sends to the server. Enter a value between 5 and 10. The default value is 10.
- Allowed loss: The maximum number of packets that can be lost without the test returning an error. Enter a value from 0 to 10. The default value is 5.
- Slow: The time in milliseconds after which the test evaluates the server's response as slow. Enter a value between 50 and 5000 ms. The default value is 500ms. If you delete the value, the test will not evaluate the response time.
For an overview of the HTTP type check output, see the article OnLine – Ping Warnings and Errors.
DNS Query Check
The DNS Query check sends a query to a specific DNS server (or one of the authoritative ones). It checks the correctness of the answer (any positive answer or a specific value) and the response time. If the response changes, the test also sends an email notification.
DNS Query check settings include:
Domain name: The full name of the domain or subdomain to check. Record type: The DNS record type to test. The test supports A, AAAA, MX, CNAME, NS, TXT, PTR, and SRV records. Expected value: The value of the record that the test considers to be correct. Enter only one value. If you need to verify multiple values, create a separate test for each of them. If you leave the field blank, the test considers any non-blank answer as correct. DNS server: The name or IP address of the server which the test will query. If you leave the field blank, the system will select one of the authoritative DNS servers of the domain name. IP protocol: Perform the test via the selected IP protocol. When set to auto (default), it prefers IPv6. Timeout: Maximum time tolerance for DNS server response. Enter a value of 1 to 5 seconds. The default value is 3 s. If the server does not respond within this time, the test returns an error. Slow: The time in milliseconds after which the test evaluates the DNS server response as slow. Enter a value between 100 and 5000 ms. The default value is 1000ms. If you delete the value, the test will not evaluate the response time. Notify about changes in DNS records: The test can send an email notification whenever a change to a DNS record is detected.
DNS Servers Check
The DNS Servers check verifies the functionalityy, response time and the zone serial numbers match on the domain’s authoritative DNS servers. It reports serious problems as an error, less serious as a warning. If the response changes, the test also sends an email notification.
DNS servers check settings include:
- Domain: The full name of the domain (without www) that the test should check.
- Timeout: Maximum time tolerance for DNS server response. Enter a value of 1 to 5 seconds. The default value is 3 s. If the server does not respond within this time, the test returns an error.
- Slow: The time in milliseconds after which the test evaluates the DNS server response as slow. Enter a value between 100 and 5000 ms. The default value is 1000ms. If you delete the content of the field, the test will not evaluate the response speed.
- DNS server change notification: The test can send an email notification whenever a DNS server change is detected.
DNSSEC Check
The DNSSEC check investigates the presence and validity of DNSSEC keys, signatures, and domain/DNS record delegation. Warns about approaching signature expiration.
DNSSEC check settings include:
- Domain name: The full name of the domain or subdomain that the test is to check.
SMTP, POP3, IMAP Checks
SMTP, POP3 and IMAP checks verify the functionality and response time of the corresponding mail server. The checks include TLS security (STARTTLS or implicit TLS), TLS certificate trustworthiness and expiration, login credentials, and server IP address check against DNSBL.
SMTP, POP3, IMAP check settings include:
- SMTP / POP3 / IMAP server: Domain name or IP address of the tested server.
- Security: Select the type of server security. Default values are explicit TLS (STARTTLS) for SMTP, implicit TLS for POP3 and IMAP.
- Port: TCP port number on which the server listens. The default values are 25 for SMTP, 995 for POP3, and 993 for IMAP.
- IP protocol: Perform the test via the selected IP protocol. When set to auto (default), it prefers IPv6.
- Username and password: Enter the full name of the email address as the username. If you leave the field blank, the check will test the functionality of the server without logging in.
- Connection timeout: Maximum time tolerance for connecting to the server. Enter a value of 1 to 5 seconds. The default value is 5 s. If the server does not respond within this time, the test returns an error.
- Response timeout: The maximum time tolerance to return a complete response from the server (including the connection). Enter a value between 1 and 10 seconds. The default value is 10 s. If the server does not return a complete response within this time, the test returns an error.
- Slow: The time in milliseconds after which the test evaluates the DNS server response as slow. Enter a value between 100 and 5000 ms. The default value is 2000ms. If you delete the value, the test will not evaluate the response time.
- Check certificate trust: The test verifies the HTTPS certificate against trusted certificate authorities and compares the certificate name to the host name. If you want to accept an invalid certificate (e.g. self-signed), uncheck this option.
- Ccheck certificate expiration: The test checks the validity of the certificate and if the validity falls below the number of days set in the certificate warning field (enter 1 - 30 days, default value 7), it sends a certificate expiration warning.
- Check block lists (DNSBL): The test checks the presence of IP addresses of HTTP servers or domains in public block lists (DNSBL).
MX Servers Check
The MX Servers check verifies the functionality and response speed of the email SMTP servers listed in the domain’s MX records. It reports serious problems as an error, less serious ones as a warning. If the response changes, the test also sends an email notification.
MX servers check settings include:
- Domain: The full name of the domain or subdomain that the test should check. The test finds the corresponding MX records from DNS.
- Connection timeout: Maximum time tolerance for connecting to the server. Enter a value of 1 to 5 seconds. The default value is 5 s. If the server does not respond within this time, the test returns an error.
- Response timeout: The maximum time tolerance to return a complete response from the server (including the connection). Enter a value between 1 and 10 seconds. The default value is 10 s. If the server does not return a complete response within this time, the test returns an error.
- Slow: The time in milliseconds after which the test evaluates the DNS server response as slow. Enter a value between 100 and 10000 ms. The default value is 5000ms. If you delete the content of the field, the test will not evaluate the response speed.
- Notify about changes of MX servers: The test can send an email notification whenever a change of MX servers is detected.
FTP Check
The FTP check checks the functionality and response speed of the file FTP server. Supports TLS security (STARTTLS or implicit TLS), checks TLS certificate trustworthiness and expiration. It also verifies the functionality of the credentials. It checks the server’s IP address against DNSBL.
FTP check settings include:
- FTP server: Domain name or IP address of the tested server.
- Security: Select the type of server security. The default value is explicit TLS (STARTTLS).
- Port: TCP port number on which the server listens. The default value is 21.
- IP Protocol: Perform the test via the selected IP protocol. When set to auto (default), it prefers IPv6.
- Username and password: Enter the name of an existing FTP account as the username. If you leave the field blank, the check will test the functionality of the server without logging in.
- Connection timeout: Maximum time tolerance for connecting to the server. Enter a value of 1 to 5 seconds. The default value is 5 s. If the server does not respond within this time, the test returns an error.
- Response timeout: The maximum time tolerance to return a complete response from the server (including the connection). Enter a value between 1 and 10 seconds. The default value is 10 s. If the server does not return a complete response within this time, the test returns an error.
- Slow: The time in milliseconds after which the test evaluates the DNS server response as slow. Enter a value between 100 and 5000 ms. The default value is 2000ms. If you delete the value, the test will not evaluate the response time.
- Check certificate trust: The test verifies the HTTPS certificate against trusted certificate authorities and compares the certificate name to the host name. If you want to accept an invalid certificate (e.g. self-signed), uncheck this option.
- Check certificate expiration: The test checks the validity of the certificate and if the validity falls below the number of days set in the certificate warning field (enter 1 - 30 days, default value 7), it sends a certificate expiration warning.
- Check block lists (DNSBL): The test checks the presence of IP addresses of HTTP servers or domains in public block lists (DNSBL).
TCP Check
The TCP check performs a basic test of a TCP connection to a specific port (without knowing and testing the application protocol). If the destination port supports standard TLS, it can check the trustworthiness and expiration of the certificate.
TCP check settings include:
- TCP server: Domain name or IP address of the tested server.
- Security: Select the type of server security. The default value is none.
- Port: TCP port number on which the server listens.
- IP protocol: Perform the test via the selected IP protocol. When set to auto (default), it prefers IPv6.
- Connection timeout: Maximum time tolerance for connecting to the server. Enter a value of 1 to 5 seconds. The default value is 5 s. If the server does not respond within this time, the test returns an error.
- Slow: The time in milliseconds after which the test evaluates the DNS server response as slow. Enter a value between 100 and 5000 ms. The default value is 2000ms. If you delete the content of the field, the test will not evaluate the response speed.
- Check certificate trust: The test verifies the HTTPS certificate against trusted certificate authorities and compares the certificate name to the host name. If you want to accept an invalid certificate (e.g. self-signed), uncheck this option.
- Check certificate expiration: The test checks the validity of the certificate and if the validity falls below the number of days set in the certificate warning field (enter 1 - 30 days, default value 7), it sends a certificate expiration warning.
SPF Record Check
If you have not yet set up an SPF record for your domain, follow the instructions in the Emails – SPF Record guide.
The SPF Record check sends a query to a specific DNS server (or one of the authoritative ones) to obtain a TXT SPF record of the domain. It checks the response and performs and the SPF record content. If the response changes, the test also sends an email notification.
SPF record check settings include:
- Domain name: The full name of the domain or subdomain that the test is to check.
- DNS server: The name or IP address of the server to which the test will send queries. If you leave the field empty, the system will select one of the authoritative DNS servers of the domain name.
- IP protocol: Perform the test via the selected IP protocol. When set to auto (default), it prefers IPv6.
- Timeout: Maximum time tolerance for DNS server response. Enter a value of 1 to 5 seconds. The default value is 3 s. If the server does not respond within this time, the test returns an error.
- Slow: The time in milliseconds after which the test evaluates the DNS server response as slow. Enter a value between 100 and 5000 ms. The default value is 1000ms. If you delete the content of the field, the test will not evaluate the response speed.
- Notify about changes in DNS records: The test can send an email notification whenever a change to the SPF record is detected.
SSH/SFTP Check
The SSH/SFTP check tests the SSH server functionality and response time. It can also verify the functionality of login credentials (name and password). It allows you to test the functionality of the SFTP file transfer protocol after establishing an SSH connection. If the response changes, the test also sends an email notification.
SSH/SFTP record check settings include:
- SSH server: Enter the domain name or IP address of the SSH server.
- Port: TCP port number on which the server listens. The default value is 22.
- IP protocol: Perform the test via the selected IP protocol. When set to auto (default), it prefers IPv6.
- Username and password: Enter the name of an existing FTP account as the username. If you leave the field blank, the check will test the functionality of the server without logging in.
- Connection timeout: Maximum time tolerance for connecting to the server. Enter a value of 1 to 5 seconds. The default value is 5 s. If the server does not respond within this time, the test returns an error.
- Response timeout: The maximum time tolerance to return a complete response from the server (including the connection). Enter a value between 1 and 10 seconds. The default value is 10 s. If the server does not return a complete response within this time, the test returns an error.
- Slow: The time in milliseconds after which the test evaluates the DNS server response as slow. Enter a value between 100 and 5000 ms. The default value is 2000ms. If you delete the value, the test will not evaluate the response time.
- SFTP test: After successfully establishing an SSH connection, you can also test the SFTP file transfer protocol.
- SSH server key change notification: The test can send an email notification whenever a SSH server change is detected.