Load Balancer - ADC

Questions on vServices, Backend Services, algorithms, health checks, client IP, routing and operations. Search for a question, filter by level or jump to a category.

01Fundamentals and Getting StartedLoad balancer, ADC and TR7 building blocks

• What is a load balancer and what does it do?LB-01-001
• I only have one server; would I benefit from using TR7 Load Balancer?LB-01-002
• What does the TR7 Load Balancer - ADC module cover, and what does it not cover?LB-01-003
• What is a vService?LB-01-004
• What is a Backend Service?LB-01-005
• What is a Backend Group, and how is it different from a Backend Service?LB-01-006
• What are Condition and Action, and what are they used for?LB-01-007
• What is a Profile, and why is it defined as a separate object?LB-01-008
• What is a Health Check, and why is it needed?LB-01-009
• What is persistence?LB-01-010
• Is a load balancer different from a reverse proxy?LB-01-011
• What is the difference between a Proxy and a Reverse Proxy?LB-01-012
• Does TR7 Load Balancer require code changes in my application?LB-01-013
• What are the most basic steps to set up my first vService?LB-01-014
• During setup, should I create the Backend Service or the vService first?LB-01-015
• Which stages does a request go through inside TR7 before it reaches the backend?LB-01-016
• What is the difference between Load Balancer and GTM; which one should I use?LB-01-017
• Can I use Load Balancer and GTM together?LB-01-018
• I'm coming from F5, Citrix, Kemp or HAProxy; what are the TR7 equivalents of concepts like virtual server, pool, node, monitor and iRule?LB-01-019
• Do I need to change my network topology to add TR7 (one-arm / two-arm / inline)?LB-01-020
• What is a Route Table; when do I need to change it for a vService or Backend Service?LB-01-021
• When does a change I make take effect; does it go live as soon as I save it?LB-01-022

02vService Types and ProtocolsHTTP, L7 TCP, Network and supported protocols

• How many types of vService does TR7 have, and how do they differ?LB-02-001
• Which vService type should I choose for my application?LB-02-002
• Should I use an HTTP vService or an L7 TCP vService for my HTTPS site?LB-02-003
• Is HTTP/2 supported?LB-02-004
• Can I load balance WebSocket traffic?LB-02-005
• Can I load balance UDP traffic (DNS, Syslog, NTP)?LB-02-006
• What are the feature differences between HTTP, L7 TCP and Network vServices?LB-02-007
• What is the difference between L7 TCP and Network (TCP - L4); aren't they both TCP?LB-02-008
• Is HTTP/3 (QUIC) supported; how is it enabled and which conditions does it depend on?LB-02-009
• Can I put my gRPC services behind TR7?LB-02-010
• Can I load balance SIP/VoIP traffic?LB-02-011
• Can I load balance an RDP server farm?LB-02-012
• Can I load balance database connections (SQL Server, Oracle, MySQL, PostgreSQL)?LB-02-013
• Can I load balance LDAP / Active Directory queries?LB-02-014
• Can I load balance SMTP / mail servers?LB-02-015
• Are messaging protocols such as MQTT, AMQP and FIX supported?LB-02-016
• Can I load balance FTP; what happens to the data channel?LB-02-017
• Can the same vService listen on both port 80 and port 443?LB-02-018
• Can I define more than one vService on the same IP:port?LB-02-019
• What does creating a vService in the Disabled state mean, and when is it used?LB-02-020
• What does a vService started in Debug Mode do; why is it only available in the HTTP vService, and what is the downside of leaving it on in production?LB-02-021
• Can I change the type of a vService later?LB-02-022
• Can I load balance protocols without ports, such as ICMP, GRE and IPsec (ANY - L3)?LB-02-023
• Can I make a vService listen on a wide port range (e.g. 4000-5000)?LB-02-024

03Frontend, VIP and Virtual HostingListening IPs, ports and domain names

• Which IP address can I use for a vService; what is the difference between an Interface IP and a VIP?LB-03-001
• What is a VIP, and when is it needed?LB-03-002
• Can I publish more than one website behind a single public IP?LB-03-003
• What is Virtual Hosting, and how does it work?LB-03-004
• How do I redirect requests for example.com to www.example.com (or the other way around)?LB-03-005
• Can I use a VIP without a cluster?LB-03-006
• Can I do Virtual Hosting with a wildcard domain (*.example.com)?LB-03-007
• In Virtual Hosting, where does a request that matches no host go?LB-03-008
• Can I serve different certificates for different domains on the same IP:443 (SNI)?LB-03-009
• What is the difference between the HTTP → HTTPS frontend protocol option and the Redirect to HTTPS action?LB-03-010
• Can I use an IPv6 address on the frontend?LB-03-011
• What do I need to do on the network side first to open a vService on an IP in a different subnet / VLAN?LB-03-012
• Why can't I type the Frontend IP manually; what should I do to use an IP that is not in the list (e.g. IPv6) on a vService?LB-03-013

04Backend Services and GroupsTarget servers, weight, backup and maintenance

• How is a Backend Service added; which information is required?LB-04-001
• When should I use a Backend Group, and when individual Backend Services?LB-04-002
• Should I create a Backend Group even if I only have one server?LB-04-003
• Can I use one Backend Service in more than one vService?LB-04-004
• What do the health colors and icons in the Backend Service list mean?LB-04-005
• What is Weight, and how should it be set?LB-04-006
• What does Maintenance Mode do?LB-04-007
• What is a Backup Service; when does it take over, and when does it step back?LB-04-008
• Can I enter a domain name (FQDN) instead of an IP as the Backend Service address?LB-04-009
• How do I see which vServices use a Backend Service ("Used in")?LB-04-010
• How do I find Backend Services that are not used anywhere (Unused Entries)?LB-04-011
• Which settings are shared at group level, and which are per server?LB-04-012
• Can I give the servers in a Backend Group their own Weight and connection limit?LB-04-013
• What is Connection Limit; what happens to new requests when the limit is reached?LB-04-014
• Can the Backend Service port be different from the frontend port (sending a request received on 443 to 8080)?LB-04-015
• What does the "Use Frontend Port" option do?LB-04-016
• What does the SSL Service option do; what is needed to connect to the backend over an encrypted connection?LB-04-017
• Can I export the Backend Services and Backend Groups lists (Export)?LB-04-018
• How do I temporarily stop all traffic to a server; can I set Weight to 0?LB-04-019
• What do the "Low" and "Standard" cipher options mean for a Backend Service that uses SSL, and which should I choose?LB-04-020
• What is the Proxy Protocol setting, and when should it be enabled?LB-04-021
• What does "Default" in the SNAT field mean; can I choose a specific SNAT IP?LB-04-022
• What is the Cookie Content field used for?LB-04-023
• Can my backends be on different networks / in different route tables?LB-04-024
• Can my backends be in a different data center or in the cloud?LB-04-025
• Can I add many servers in bulk?LB-04-026
• If I define more than one Backup Service, is traffic distributed across all of them?LB-04-027

05Load Balancing AlgorithmsHow traffic is distributed across servers

• Which load balancing algorithms are supported?LB-05-001
• What is the default algorithm?LB-05-002
• Which algorithm should I choose; is there a decision guide?LB-05-003
• What is the difference between Round Robin and Weighted Round Robin?LB-05-004
• When is Least Connection better than Round Robin?LB-05-005
• How do I distribute load proportionally across servers with different capacities?LB-05-006
• How do Least Response Time and Least Bandwidth work; why do they sometimes behave like Least Connection?LB-05-007
• What is the First algorithm used for?LB-05-008
• Does the Random algorithm have any practical benefit?LB-05-009
• Can the Source algorithm be used instead of persistence?LB-05-010
• Which algorithm is recommended for database connections?LB-05-011
• What is the RDP Cookie algorithm?LB-05-012
• Why is traffic not distributed evenly across the servers?LB-05-013
• All users coming from behind a corporate NAT go to a single server; why?LB-05-014
• What are the URI, URL Param and HDR algorithms for; in which scenario are they used?LB-05-015
• What do the entries marked "(Self-persistent)" in the algorithm list mean?LB-05-016
• What does the Hash Consistency option do in hash-based algorithms?LB-05-017

06Session PersistenceKeeping a user on the same server

• How do I know whether my application needs persistence?LB-06-001
• Which persistence methods are available?LB-06-002
• What is the difference between New Cookie and Current Cookie?LB-06-003
• How does Hash persistence work?LB-06-004
• What is Session Affinity Manager (SAM); how is it different from classic cookie persistence?LB-06-005
• Which persistence options are available for an L7 TCP vService?LB-06-006
• How does L4 Persistence work on a Network vService; how is the duration set?LB-06-007
• Persistence is enabled, but my users still end up on different servers; why?LB-06-008
• Persistence is causing uneven load distribution; what can I do?LB-06-009
• Can sessions be rebalanced when servers are added or removed?LB-06-010
• How is persistence achieved for clients that do not support cookies (mobile apps, API clients)?LB-06-011
• Does saving a configuration change reset the persistence tables?LB-06-012
• What do Rebalance and Clear All do on the Session Affinity Manager (SAM) tab?LB-06-013
• Why does SAM require at least two Backend Services?LB-06-014

07Health CheckMeasuring server health

• What does a Health Check do; what happens if I don't assign one?LB-07-001
• What is the default health check behavior (Period, Timeout, Required Successes, Required Failures)?LB-07-002
• Which health check types are supported?LB-07-003
• What is the difference between a TCP port check and an HTTP check; which should I choose?LB-07-004
• How many seconds does it take for a server to be considered "down", and how do I calculate it?LB-07-005
• How do I expect a specific status code (e.g. 200, 302) in an HTTP health check?LB-07-006
• How do I verify a specific text (e.g. "OK") in the response content?LB-07-007
• What is "Expect Negative Result" used for?LB-07-008
• Can certificate verification be done in an HTTPS health check?LB-07-009
• Can I check a different IP/port of the server for the health check (Use Different IP for Health Check)?LB-07-010
• Which source IP are health check packets sent from; can I change it?LB-07-011
• Which IPs should I allow on the server firewall for health checks?LB-07-012
• How should I set the Period, Timeout, Required Successes and Required Failures values?LB-07-013
• What are the recommended values for slow-responding services (databases, reporting)?LB-07-014
• How do I health check DNS servers?LB-07-015
• How do I see the health check history (when a server went down/up)?LB-07-016
• What does Enable HC Logs do; should I turn it off?LB-07-017
• If I change a health check profile, which Backend Services are affected?LB-07-018
• What do users see if all servers are down; can I show a custom page instead?LB-07-019
• What kind of /health endpoint should I design in my application for health checks?LB-07-020
• How do I health check UDP services other than DNS (UDP scenario, Hex/Base64/text)?LB-07-021
• Can authenticated / STARTTLS checks be done for LDAP, SMTP and FTP?LB-07-022
• The server is running, but TR7 shows it as down; why?LB-07-023
• The server has failed, but TR7 still sends traffic to it; why?LB-07-024
• The health check keeps going back and forth between up/down (flapping); what should I do?LB-07-025
• Health check requests are filling up my backend logs; what can I do?LB-07-026
• Can I assign more than one health check to a Backend Service?LB-07-027
• How many seconds does it take for a health check result to affect traffic?LB-07-028
• Can I validate a JSON response field by field in a health check (Content Check Mode: JSONata Expression)?LB-07-029
• Can I specify a Host / SNI in a health check (Virtual domain)?LB-07-030
• Can I see only status changes in the health check logs (Only Change Logs / All Logs)?LB-07-031

08SSL/TLS and CertificatesTermination, passthrough, certificate management

• What is SSL offloading (termination), and how is it set up?LB-08-001
• How do I upload my certificate to TR7; which formats are supported?LB-08-002
• How do I redirect HTTP to HTTPS?LB-08-003
• Can I use a wildcard certificate?LB-08-004
• How do I get a warning before a certificate expires?LB-08-005
• What is SSL passthrough; when should I use passthrough instead of termination?LB-08-006
• What is SSL bridging; how do I also encrypt the traffic to the backend?LB-08-007
• How do I choose between termination, passthrough and bridging?LB-08-008
• How do I add the intermediate certificate chain?LB-08-009
• Can I manage Private Keys separately (Private Key Library)?LB-08-010
• Can I create a CSR on TR7?LB-08-011
• Can I get certificates automatically with Let's Encrypt / ACME?LB-08-012
• Can I attach more than one certificate to a vService; how is the right certificate selected (SNI)?LB-08-013
• When I renew a certificate, do I need to replace it on each vService one by one?LB-08-014
• What is a TLS Security Profile, and what does it configure?LB-08-015
• How do I disable TLS 1.0/1.1; is TLS 1.3 supported?LB-08-016
• How do I disable weak ciphers?LB-08-017
• How do I add HSTS?LB-08-018
• After switching to HTTPS, pages show a "mixed content" warning; how do I fix it?LB-08-019
• The browser says "certificate not trusted"; what are the possible causes?LB-08-020
• How do I tell if the certificate chain is incomplete?LB-08-021
• My backend uses a self-signed certificate; is that a problem?LB-08-022
• Which DNS providers are supported for the ACME DNS challenge?LB-08-023
• Can I import/export cipher lists?LB-08-024
• What should I do to get an A+ from SSL Labs?LB-08-025
• Can I authenticate clients with client certificates (mTLS)?LB-08-026
• How do I add my own internal CA to TR7?LB-08-027
• Can I verify the backend certificate when connecting to the backend over HTTPS?LB-08-028
• I need to send SNI when connecting to the backend; how do I set it up?LB-08-029
• Is there a difference between TCP + TLS termination on L7 TCP and termination on an HTTP vService?LB-08-030
• With passthrough, can I route to different backends based on SNI?LB-08-031
• Can I route or block traffic based on TLS version or cipher?LB-08-032
• How do I filter certificates that have expired or are about to expire (Expiry Health)?LB-08-033
• What does the vService do if the certificate I uploaded has an error?LB-08-034
• Can I use TR7 as an internal CA to issue, automatically renew and revoke certificates?LB-08-035
• What is the difference between HTTP-01 and DNS-01 in ACME; why is DNS-01 required for wildcards?LB-08-036
• Is OCSP Stapling supported?LB-08-037
• Is post-quantum key exchange supported?LB-08-038
• Can I reject requests whose SNI and Host Header do not match (domain fronting) (SNI/Host Validation)?LB-08-039

09Client IP, SNAT and XFFCarrying the real client IP

• Why do my backend servers see all requests as coming from TR7's IP?LB-09-001
• What is SNAT, and why is it used by default?LB-09-002
• How do I see the real client IP on the backend?LB-09-003
• How is X-Forwarded-For enabled; what do I need to do on the backend side (Apache / Nginx / IIS logs)?LB-09-004
• What is the difference between X-Forwarded-For and Proxy Protocol?LB-09-005
• How do I pass the real client IP for non-HTTP TCP services?LB-09-006
• There is a CDN such as Cloudflare / Akamai in front of TR7; how do I get the Real client IP (trusted proxy)?LB-09-007
• What is the difference between the "Real IP from" options in the Trusted Proxy profile (X-Forwarded-For (last / most trusted), X-Forwarded-For (first), Custom Header)?LB-09-008
• Do TR7 and the backends have to be on the same L2 network?LB-09-009
• What kind of security risk arises if Trusted Proxy is misconfigured (IP Spoofing)?LB-09-010
• Which components use the IP resolved by Trusted Proxy (log, condition, WAF, Bot & DDoS Protection)?LB-09-011
• Is it possible to work without SNAT (transparent mode); what are the requirements?LB-09-012
• What is Direct Server Return (DSR); what preparation is needed on the server side?LB-09-013
• Why does return traffic have to flow through TR7 in Route Mode?LB-09-014
• Choosing the LB Mode: how do I decide between DSR, Route Mode and SNAT?LB-09-015
• What is the difference between the SNAT options on a Backend Service (Default, Use Client IP, Use Device IP)?LB-09-016

10Conditions, Actions and RoutingConditional routing and traffic rules

• What is the difference between a Condition and an Action?LB-10-001
• What is Content Switching?LB-10-002
• How do I route to different servers based on the URL path (e.g. /api → API servers)?LB-10-003
• Can I route based on the Host Header?LB-10-004
• Where does traffic go if no condition matches?LB-10-005
• What is the difference between Conditional Backend Services and Default Backend Services?LB-10-006
• Can I route based on an HTTP Header, cookie or query parameter?LB-10-007
• Can I route clients to a different backend based on their country / city?LB-10-008
• Can I send mobile devices to a separate backend?LB-10-009
• Can I route based on the browser's language preference?LB-10-010
• How do I combine multiple conditions with AND / OR?LB-10-011
• Can I use a condition in negated form ("if not")?LB-10-012
• In what order do Actions run; how do I change the order?LB-10-013
• If an action blocks or redirects traffic, do the subsequent actions run?LB-10-014
• What is the difference between On Request and On Response actions?LB-10-015
• Why is my Action not triggering?LB-10-016
• Can I use the same condition in more than one vService?LB-10-017
• When I change a condition or an action, which vServices are affected?LB-10-018
• How do I do a canary or blue-green deployment?LB-10-019
• Can I route only users coming from the internal network (specific IPs) to a test server?LB-10-020
• Can I send only a certain percentage of traffic to a new version?LB-10-021
• Can I make decisions based on backend response time or response status code?LB-10-022
• What is a Smart Variable; how is it used in conditions and actions?LB-10-023
• What are Dynamic Condition and Dynamic List used for?LB-10-024
• Can I send a copy of the traffic to a test environment (Traffic Mirroring)?LB-10-025
• How do I change the evaluation order of Conditional Backend Services blocks?LB-10-026
• Can I see how many times an action has been triggered (hit counter, Action Hits)?LB-10-027
• How many Traffic Mirroring actions can I use on a vService at most?LB-10-028
• Why doesn't a Location Redirection or User Authentication (On HTTP request) action work if I add it without a condition?LB-10-029
• Can I apply different rules per destination IP on a vService published on multiple IP addresses (Destination IP)?LB-10-030
• If a vService listens on multiple ports, can I apply a different action or Backend Service per port (Destination Port)?LB-10-031
• Can I show different content or route to a different Backend Service based on the client's operating system (Operating System)?LB-10-032
• Can I act on the size of the response returned by the Backend Service (Response Size (bytes))?LB-10-033

11HTTP ManipulationHeaders, redirects and error pages

• How do I redirect a specific URL to another URL with a 301/302?LB-11-001
• How do I set up a redirect that adds or removes www?LB-11-002
• How do I publish a maintenance page?LB-11-003
• Can I show a custom error page when the backend returns 404 or 500?LB-11-004
• Can I add, remove or change HTTP Headers in a request or response?LB-11-005
• How do I do an SEO-friendly migration from an old domain to a new domain?LB-11-006
• Can I rewrite the URL path before it reaches the backend (rewrite)?LB-11-007
• What is the difference between Set Path and Set Path + Query?LB-11-008
• How do I hide headers that reveal server information, such as Server and X-Powered-By?LB-11-009
• Can I add security headers (CSP, HSTS, X-Frame-Options) without touching the backend?LB-11-010
• Can I show a custom page for 503/502/504 errors generated by TR7 itself?LB-11-011
• On an error, is it better to show a page or to redirect?LB-11-012
• What is the Content Pages profile; how do I prepare my own HTML page?LB-11-013
• Can I return content directly for certain requests without going to the backend (Show Content)?LB-11-014
• How do I make the admin panel accessible only from specific IPs?LB-11-015
• Can I automatically add the Secure, HttpOnly and SameSite attributes to cookies?LB-11-016
• Can I change a header value with a regex?LB-11-017
• My backend is sensitive to the letter case of header names; does TR7 change them (Keep Header Names / HTTP 1.0 Header Compatibility)?LB-11-018
• Can I modify the response body (e.g. inject a script into HTML, mask national ID / card numbers)?LB-11-019
• Is it possible to reject or silently drop a connection at the TCP level (TCP Connection Management)?LB-11-020
• Are there ready-made maintenance / error page templates?LB-11-021

12Performance and OptimizationCache, compression, limits, bandwidth

• Which features does TR7 offer to speed up my application?LB-12-001
• Can I do caching on TR7; what are the default settings?LB-12-002
• How is compression (GZIP / DEFLATE) enabled; which content types should be compressed?LB-12-003
• What do the values in the Timeouts profile (HTTP Keepalive Timeout, HTTP Request Timeout, Connect, Server, Client, Queue, Tunnel(Websocket) Timeout, Client FIN, Server FIN) mean?LB-12-004
• What is the vService Limits profile; what are the default limits?LB-12-005
• Which content gets cached; how do I define cache rules?LB-12-006
• How do I know a response came from the cache (Cached(HIT) Header Name, default value TRCACHE)?LB-12-007
• Are the query string and Host Header part of the cache key; can I change this?LB-12-008
• How do I prevent user-specific content from being cached by mistake?LB-12-009
• Old content is still being served after an application update; what should I do?LB-12-010
• What should the Compression Level be; what is its effect on CPU?LB-12-011
• Why is the request cut off during long operations (report, file upload); which timeout should I increase?LB-12-012
• My WebSocket connections drop after a certain time; what should I do?LB-12-013
• What happens when the connection limit is reached?LB-12-014
• Can I limit bandwidth (download / upload)?LB-12-015
• The site is slow; how do I tell whether the problem is in TR7 or in the backend?LB-12-016
• What is Dynamic Caching, and when should it be used?LB-12-017
• What does the Offloading option in the Compression profile do?LB-12-018
• How do cache and compression work together?LB-12-019
• What is HTTP TCP Multiplexing; how does it reduce the number of backend connections?LB-12-020
• What should I consider in the Timeouts and vService Limits profiles for Microsoft Exchange (OWA / ActiveSync)?LB-12-021
• How does the queue work; how long do requests wait at most?LB-12-022
• What is Max. Failed Connection Retries used for?LB-12-023
• What is Buffer size used for; when should I change it?LB-12-024
• What is QoS; how do I reserve dedicated CPU/memory resources for critical vServices?LB-12-025
• What do the Memory Limit, Cores, CPU Priority, Cpu usage limit and Inline Mode settings in QoS do?LB-12-026

13Security and Access ControlSecurity controls within the LB scope

• How much security does the Load Balancer module provide on its own; when do I need a WAF?LB-13-001
• Can I block traffic from specific countries?LB-13-002
• Can I block specific IPs/CIDRs or allow only them?LB-13-003
• How do I attach WAF, L7 DDoS & Threat Protection and AGS to a vService?LB-13-004
• Can I block by ASN?LB-13-005
• Can I block known malicious IPs (IP Reputation / blacklist category)?LB-13-006
• How do I recognize and handle Tor exit nodes, VPN/proxy addresses and data center (cloud/hosting) IPs separately?LB-13-007
• Can I do rate limiting (X requests per second per IP)?LB-13-008
• How does the Quarantine Action work; how long is a client that exceeds the threshold blocked?LB-13-009
• How do I see the clients in quarantine?LB-13-010
• How do I detect bots; can I allow good bots (Googlebot etc.) and block bad ones?LB-13-011
• Can I verify humans with a CAPTCHA?LB-13-012
• Can I block requests that contain debug/test parameters?LB-13-013
• I am blocking legitimate users by mistake; how do I find out?LB-13-014
• Can I apply rate limiting based on a key such as an API key / token?LB-13-015
• Can I take automatic action when the number of requests / connections suddenly increases?LB-13-016
• Can I block large requests (e.g. above a certain size)?LB-13-017
• Can I look for and block specific content in the request body (JSON / XML / form)?LB-13-018
• Can I prevent sensitive data (credit card, national ID number) from leaking out in the response?LB-13-019
• How do I see how many times a client has failed Advanced CAPTCHA and how close it is to quarantine?LB-13-020
• How do I exempt specific IPs, networks or countries from L4 DDoS protection (Whitelist & Known Peers)?LB-13-021
• How do I limit the number of concurrent TCP connections from a single source in L4 DDoS; what does the Zombie TCP setting do?LB-13-022
• How do I see sources that were quarantined in the past by L4 DDoS and why (Quarantine History)?LB-13-023

14High Availability and ClusterCluster, VIP and failover

• Is TR7 itself a single point of failure; how do I set up Load Balancer redundantly?LB-14-001
• How is a VIP defined after the cluster is set up?LB-14-002
• How does a cluster work?LB-14-003
• Is the configuration automatically synchronized between cluster members?LB-14-004
• What does a status circle split in two mean in the vService list in a cluster?LB-14-005
• What is the Master/Slave role on a VIP?LB-14-006
• What should I watch out for when taking a device in the cluster into maintenance?LB-14-007
• For redundancy across data centers, should I use Load Balancer or GTM?LB-14-008
• When a failed device comes back, does the VIP automatically move back to it?LB-14-009

15Monitoring, Logging and ReportingDashboards, logs, notifications and reports

• Where do I monitor the current status of my vService?LB-15-001
• Which metrics are on the vService dashboard?LB-15-002
• What does the Live Stats screen show?LB-15-003
• What is the difference between HTTP logs and TCP logs?LB-15-004
• Can I get notified when a vService goes down; which channels are available (SNMP, e-mail, SMS)?LB-15-005
• How is a report created; which formats are available (HTML, PDF, XLSX)?LB-15-006
• Can I see which connections are currently open (vService Sessions)?LB-15-007
• What does the Data Flow Panel on the right of the vService screen show?LB-15-008
• How do I find out from the logs why a request failed (termination state)?LB-15-009
• What does Debug Mode record; how long should I keep it on?LB-15-010
• How do I find the requests of a specific client IP in the logs?LB-15-011
• How do I send logs to a SIEM (Syslog)?LB-15-012
• Which HTTP and TCP log formats are supported (Standard, Apache Combined, Apache VHost, CEF, TR7 JSON, TR7 WAF, Manual JSON, Manual CEF, Manual log line)?LB-15-013
• Can I receive reports regularly by e-mail?LB-15-014
• Can I get notified when a certificate is about to expire or a performance threshold is exceeded?LB-15-015
• How long are logs kept on the device?LB-15-016
• Can I define my own log format?LB-15-017
• How do I reduce log volume (silencing health check and static file logs)?LB-15-018
• Can I mask IP addresses in the logs for KVKK / GDPR?LB-15-019
• Can I send flow data with IPFIX?LB-15-020
• Can I monitor TR7 metrics with Prometheus / Grafana?LB-15-021
• What kind of statistics can I collect with Advanced Traffic Inspection?LB-15-022
• Can I customize the vService dashboard with templates?LB-15-023
• Why can't I see the Report tab?LB-15-024
• Can I define advanced notifications based on source IP, country, ASN or subnet (Advanced Notifications)?LB-15-025
• What does "Partially Healthy" mean on a Backend Group dashboard; how do I find which server in the group has a problem?LB-15-026

16TroubleshootingCommon errors and diagnosis

• Users see "503 Service Unavailable" / "No Available Server"; what should I do?LB-16-001
• The vService cannot be reached at all; what should I check step by step?LB-16-002
• It works when the backend is accessed directly but not through TR7; why?LB-16-003
• The change I made does not seem to take effect; what should I check?LB-16-004
• I get 502 Bad Gateway; what are the possible causes?LB-16-005
• I get 504 Gateway Timeout; which timeout should I check?LB-16-006
• A backend shows as down; how do I diagnose it?LB-16-007
• The site became slow behind TR7; where should I start?LB-16-008
• I get a certificate error; how do I diagnose it?LB-16-009
• Legitimate users are being blocked; how do I find which rule is blocking them?LB-16-010
• Traffic is not distributed evenly across the servers; how do I investigate?LB-16-011
• The Health Check is "up", but users get errors; why?LB-16-012
• An infinite redirect loop occurred; why?LB-16-013
• My application keeps sending users back to the login screen (the session is lost); why?LB-16-014
• Large file uploads fail; why?LB-16-015
• The backend application generates http:// in absolute URLs; how do I fix it?LB-16-016
• How do I follow a specific user's problem in live traffic?LB-16-017
• Which information should I collect before contacting TR7 support?LB-16-018
• Can I capture packets on TR7 and download them as a pcap (tcpdump)?LB-16-019
• How do I download the encrypted diagnostic bundle for the support team (Encrypted Support Bundle)?LB-16-020
• What does the configuration error(s) warning in the vService preview (DNS Resolution Error, Port binding error) mean; where does Port Collision appear?LB-16-021
• How do I test from TR7 whether a server's port is reachable?LB-16-022
• How do I check which IP address TR7 resolves a domain name to?LB-16-023
• Can I run a load test against a vService or a Backend Service from TR7?LB-16-024
• How do I test from TR7 which TLS versions and ciphers a server supports?LB-16-025

17Operations and ManagementBackup, search, bulk operations

• How do I read the entire configuration of a vService on a single screen (Load Balancer Management)?LB-17-001
• Which profile types are there; which vService types can they be used with?LB-17-002
• What is the difference between temporarily disabling a vService and deleting it?LB-17-003
• Can I export lists as Excel, CSV or PDF?LB-17-004
• How do I understand the impact of changing a profile before I change it ("Used in")?LB-17-005
• Is it right to use the default profiles as they are in production?LB-17-006
• How do search, RegExp search and column-based search work on list screens?LB-17-007
• Can I back up and restore the configuration?LB-17-008
• Can I see who made changes and when?LB-17-009
• Can I define users who only have monitoring rights, or who can manage only specific vServices?LB-17-010
• What are the naming recommendations when managing many vServices?LB-17-011
• Can I manage the Load Balancer configuration via CLI or API?LB-17-012
• How are the lb commands grouped in the Web CLI (service, backend, backend-group, hc, certificate, ...)?LB-17-013
• How are array / object fields (e.g. listen) entered in the CLI?LB-17-014
• Can I enable, disable or delete multiple vServices at the same time?LB-17-015
• Can I create a new action, health check or SSL profile without leaving the vService form?LB-17-016
• How is a quick search done in the menu and across vServices (Alt+T)?LB-17-017
• What does Reload in the right-click menu do; how is it different from Disable / Enable?LB-17-018
• Can I restart a vService without interruption (soft / hard restart)?LB-17-019
• How do I see the change history of a single vService or Backend Service?LB-17-020
• Can I change the same field on multiple objects at once?LB-17-021
• How do I make sure a user edits only the vServices assigned to them and does not touch Backend Services and certificates?LB-17-022
• How do I expand TR7's data disk on a virtual machine; how do I get a disk I newly added recognized?LB-17-023
• I lost access to the management interface (Allowed Networks); how do I restore it from the CLI?LB-17-024
• Is it necessary to clear the memory cache (drop caches); when is it done?LB-17-025